Let's kick a dead horse -- how do you make a HRD sound good?

I returned with JJ gold pins, replaced the speaker with a C12N, and turned the bias up about 8%. Really very happy with it. I use it as a clean platform with an Xotic AC on constantly at a low gain setting, either pedals used as needed.

Honestly, if you'd have to pay someone to do deep mods of the amp, you might be best to sell it and buy an amp that is not a turd. IMO, YMMV, etc.

Before you get out the soldering stick, test that amp with as many other speakers as you can. No need to pull the speaker; simply disconnect it and plug in other speaker cabs or speakers in other combos.

Flabby low end can be the speaker. It could be one of the tubes. It can be a weak output transformer. It may be leaky filter caps/coupling caps.

It's always best to try to isolate the problem first, rather than do monkey-flinging-poo thing to see what sticks to the wall.

That's the thing, I don't really have any other speakers that would be appropriate for the amp around to try.  To try one, I'd probably have to buy one.  It seems like most speaker changes I've seen online have been to some sort of Celestion Greenback type speaker.  I haven't seen many folks mention C12N speakers.  I did some searching, it looks like the Celestions are more Marshall, and the C12N are more Fender Blackface era?

"It's always best to try to isolate the problem first, rather than do monkey-flinging-poo thing to see what sticks to the wall."

That's what I'm trying to do, ask around to see what actually has worked for people.  It's nice that in a forum like this you can ask follow-up questions.

"Flabby low end can be the speaker. It could be one of the tubes. It can be a weak output transformer. It may be leaky filter caps/coupling caps."

I've never been very happy with the amp's low end, even when it was new.  Assuming the factory QC checks were done correctly, that would probably rule out the output transformer. 

It is 23 years old now, I suppose the caps could be going bad.  There is a popular mod to increase the filter capacitance, and I think that's supposed to improve the low end.  Anybody ever do this?

It might be a tube.  I did replace V1 with an 12AT7 (ECC81 from JJ).  That didn't really alter the tone at all, but it did improve the volume response, which was expected.  The other two are the original Fender labeled 12AX7s.  The power tubes are the original Sovtek 5881WXTs that Fender relabeled. 

Ok, i dont want to use the quote function so...I wont. I put in a matched set of JJ gold pins. Their site can probably do a better job detailing what they are and are not.
No, not a celestion. Jensen c12n. Kind of a throw back but it worked for me.
If I recall correctly original bias was not quite 60. But 8% of spec. I tried a little higher and did not like the added buzz.
I have not had the other issues you describe.
At this point my only complaint is the volume control. I just live with it.
Edited to add,oh yeah...the gain and more gain features dont get used because, as they say in France, they blow.

Check out the Jensen offerings here:

www.tubesandmore.com/

Some, if not all, have sound clips too.

I actually ended up ordering a Celestion G12T-75. It's supposed to arrive on Thursday.

I watched a bunch of youtube videos on speaker shootouts. My favorites were vintage EVM12Ls, but that would be pretty silly to put in a HRD. I liked the tone of the G12T-75 pretty well, so I figured I'd give it a try.

The speaker was delivered last Wednesday, I put it right into the cabinet that night. I've been playing it for a week now. I have to say I like the new tone much better. The general response it a lot "tighter" now than it was with the stock Eminence speaker. I use it exclusively on the Clean channel as either a pedal platform or clean. It still gets overly bass-y if I crank the volume when clean, but I don't usually crank it up that much, as it's way too loud.

I suppose I may try the one mod where you tied the top pin of the Mid pot to the wiper pin, as to reduce the drop resistance that the Bass circuit goes though. As it is now, the Bass circuit drops through the entire 25K Mid pot. With the mod, it drops through whatever you have the Mid pot set to.

I would do it now, but I don't want to pull the circuit board out of the amp, as that is a pain. If it was easy to get to the Pot pins from the topside, I would go ahead and do it, but as it is, I'll wait and see how it goes.

That mod increases the range of the bass control, in that it can cut more bottom end out. If you currently set the bass control to minimum and it's still too much bass, then it's worth a try.
It's most useful with a bassy cab (obviously!), like a closed back 4x12. With a 12T75 in a small open back combo cab, I wouldn't expect much benefit.

I used to have that same amp around 1994 when they first came out as Blues Deluxe. Reading all the postings until the one above this, I was going to say that it's due for power supply filter cap change-outs. Do not wait until they fail; that would be a big mistake.
There's no biasing involved with 12AX type tubes, only the two power tubes. Reasonable care with ribbon cables should be enough. It's a PITA to pull that amp apart. Next time you do open it, inspect the resistors on the +/-16 Vdc power supplies. They get so hot they often unsolder connections on the board and you get strange channel switching problems. The solution is to unsolder then remount them higher off the surface of the board.

In the mid-2000s while supporting a family and working a full-time job, there I was with a lone Telecaster and a 2001 HRDeluxe. I had to make the gear work. For about 6 yrs I gigged that HRD to Hell and back. I find all HRD amps to be kinda mismatched when it comes to the bass response in the clean channel vs drive channel. After a few speaker swaps, I got good results using speakers in the range of 80 Hz - 4 kHz. I think that is the key. Anything larger, I never could get the Drive channel to have the same bass response as the Clean channel. And it bugs me if I can't use all the amp. Surprisingly the Stock Fender OEM Eminence speaker is a decent fit for the amp. It's in the range of 80 Hz - 4 kHz. I found playing live... speakers in the 80Hz -4kHz sit really well in the band's mix. Right where the guitar should be. IMO, live... speakers in the 80 Hz - 4 kHz range record really well too.

The other thing guitarist forget about... The sound guy is going to buff or nerf your tone according to what's going on with the rest of the band in relation to the dynamics of the venue anyway.

So on stage, if I get a decent tone I'm happy.

My method is rather aggressive.

I gut them and build channel 2 of a Vibrolux reverb in the chassis.
Fair amount of metal work involved.

No one else believe in gutting those unreliable, only sound good when the planets are aligned things?

:>)