DBX Expander

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

Markus,

The first this I would do is have the Reel to reel serviced. I know a Teac genius if you need a name. Even the cheapest Teacs were very good. I personally use a 3300SX and find it amazingly quiet and wonderfully dynamic. The only reel to reel that I have heard that I feel sounds BETTER is an Otari MX5050 (any version). Those are outstanding.

dbx NR (Type I or Type II) pretty much requires good equipment to start out with. The system is not tolerant with an unstable/mis-aligned tape transport, or being creative with the record levels printed to the tape. It exaggerates the problem of bad heads, intermittent loss of high frequencies, etc.

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

Opalchip,

Nice read about the dbx gear. Thanks.

The compression on the 5bx sounds useful for apartment dwellers or others that must listen to wide range recordings at lower volumes.

I have a 3bx and used to have a 118 single band expander/compressor. 1 band was rough, but 5band expansion and compression sounds like dynamite if adjusted correctly.