DBX Expander

FYI, a 5bx just sold on Ebay tonight for $1100 which was actually cheap considering it's condition. I would have bid on it, just to have a 2nd unit - but I figure my wife would've ridiculed me perpetually - so I restrained myself.
Anyway, there was an interesting link provided by the seller, which is a "white paper" giving many details about the unit. Here it is for anyone who is interested:

http://forums.klipsch.com/forums/storage/4/929253/dbx%205BX-DS%20Marketing%20Notes.pdf

Well, I totally disagree with the 2 comments above. I have demo-ed properly adjusted DBX DS Series expanders for at least 15 "vinyl people" - and only ONE did not hear a dramatic improvement in A/B auditioning. Yes, they will "pump" if you overdo the levels - so don't overdo it.

If you bi-amp vertically, you can also just use them on the mids and highs, eliminating any bass pumping - but I have not found this to be an issue. Factors to consider here are the Damping Factor of you amps, and also the speakers themselves. Mine are sealed box bass cabinets, and pumping has not been a problem. Transmission line and ported cabinets may be more of an issue.

I consider the DBX an absolutely essential part of my system. Many of the recordings of the '70's and '80's were run through STACKS of DBX, or similar, equipment in the studio - EQ, compression, and peak limiting AT A MINIMUM! Proper use of one more quality device that attempts to reverse the "processing" on the output side does "color" the sound (that's what it's supposed to do) but not detrimentally IMO - just the opposite. They DO include op-amps in the circuit, but again, nobody who has heard mine can point out any negatives. One guy who is a hard core minimalist simply decided he liked the sound without the 3BX better, but admittedly had no rational explanation. Then on a 2nd visit, he was pretty much neutral on the 5BX. Quite a few people have bought 3BX's immediately after hearing mine.

That being said, a DBX will not elevate a cheaper, worn out, or misalignes RtR to the level you're looking for.

Unless you have much money to burn, try a 3BX-DS first. The DS version is the ONLY one to consider - the older ones are not as good. It should only cost around $200 to $225 plus shipping, on Ebay. There are lots around and they're affordable. If you don't like it, you can very easily resell it for what you paid.
A mint 5BX may cost you close to $1500 or more, so it's a bit riskier to start out with - especially if buying from an Ebay dealer and/or shipping via UPS or Fedex is part of the equation! The 5BX's Impact Restoration circuit is better, but the 3BX-DS's Dynamic Range Expansion is better IMO. So it's kind of a toss up anyway. I know someone who uses one 3BX on each channel and the results are superb.

First - $700 is ridiculously high for a 3bx. The best 3bx, which is the DS series, can be bought for $250 (or less) on Ebay very easily and I've never ever heard of one needing to be "refurbed". So now I'm a little suspicious of your tech guy's ethics.
Second - the heads on a 4010s should never need alignment from what I understand. They are totally fixed by attachment to a base plate. Moving them around once they have wear on them (without resurfacing them first) can screw up your playback, and possibly your tapes. You can also check whether your tech did this by popping the cover off and seeing whether the locktite glue on the set screws has been disturbed/cracked.
Read these two links carefully. Note in the 2nd thread that there are potential preamp issues:

http://www.angelfire.com/electronic2/vintagetx/
http://www.audiokarma.org/forums/archive/index.php/t-96374.html

If you dial it in properly, I doubt you will want to sell it.
Looking at your system, you may not be into compression*** anymore - but the Impact Restoration on any analog recordings, when not overdone, is addictive. I have my 3BX-DS in the closet, just as a backup in case God Forbid, my 5bx ever has a problem.

***One really valuable use for compression is if you make CD's for listening in your car. By compressing, you can actually hear the quieter sections over road noise, without the louder passage blowing you away. I often wondered why I like the FM radio for car listening better than the built in CD player - that's why.

I certainly don't want to sell mine, but the 3bx-ds is very easy to find on Ebay. Seems there's at least one a week. And there IS another 5bx on Ebay right now, which is very unusual - they only show up about once or twice a year, and now there have been 2 in 2 weeks. With the economy and market diving, stuff may be coming out of closets...
The current one is missing it's remote control (which is nice, but not at all necessary), so it should go for a bit less than the last one.

I use my unit primarily for the Impact Restoration. The effect of the IR is to really open up the leading edge of sounds that already have a fast attack. High hats, cymbals, plucked strings, bass thumps really sound much more like live music. Until you A/B back and forth, you don't realize what you've been missing - once you do, there's no going back.