Yesterday, without any warning, the backside of the driver's electrically controlled seat stopped moving up and down in our 1995 850 Turbo sedan (bought with 19 miles and closing on 170k miles). All other electrically controlled functions of the driver's seat are working fine. Is there any possibility that 'something' got disconnected? Is this something I could try and fix myself? Your help and suggestions would be greatly appreciated.

The car is running great (i.e., except for the 'mishap' mentioned in the previous paragraph) and a recent request to sell it was turned down.

Parts are about $75 and labor is $210 @ an independent.

If you hear the motor running when you try to adjust the seat back and nothing happens, it is a common problem that has plagued 850s for a long time. It can be fixed at home.
Read this first:

http://volvospeed.com/Repair/seatcable1.php

Just cut off the hog rings and toss them. Use plastic cable ties to put the seat cover back again.
Because the cable goes from one side of the seat to the other (poor design), it is long enough to remove a little of the metal shiething on either end and put it back on. It may not be necessary to remove the entire seat back cover or remove the headrest.
If you need to remove the headrest, it is better for 2 people to do it. Just feel below the headrest supports about 4 inches and push on the plastic tab, then pull up on the headrest. It will take a lot of effort and trial & error.

Be careful with the cover off of the seat controls. There is a red plastic thing stuck inside the cover, use it to lock the SIPS bag activator so you dont accidently bang it and set off the air bag.

This job is time consuming, but very satisfying to DIY. The dealer wants much too much money because they don't like doing things outside of the engine compartment. They will replace the cable even if it is not needed.

Klaus
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I still miss my 164 and my 854T. Just driving a V70R :)

As Klaus said, this is a common problem with 850's. My '95 854T came with the same problem. The absolute worst part is the hog rings. You need some really strong cutters or the proper pliers (I resorted to buying some cheap heavy duty snips - they worked well with the proper force) It is hard to navigate at the bottom of the seatback.

I used plastic ties as Klaus suggested. I think I interlocked two at each location because I was having trouble flexing the end in and around while keeping the seatback and bottom separated enough to work. I can see how an experienced person could reintall hog rings, but I wouldn't recommend you try.

The instructions are excellent. In my case, the cable had been replaced and was not put in correctly. Just work methodically and slowly and you should be fine. Don't do this job when you are in a hurry. I did it while caring for my elderly mother and it was nerve wracking. Good luck. Don