FYI, I recently started having trouble with the DC-DC converter circuit in my TS-850 as well. (Luckily I still have that dusty old TS-950SDX backup radio to tide me over.

) While deciding what to do to it, I stumbled across this article:
http://oz1bxm.dk/TS850/ts850-repair.html
It states that the reason for the failures has to do with the hfe (forward current gain) of the transistors degrading. Changing the resistors helps but seems not to be the best fix. The article recommends replacing the whole circuit with a DC-DC converter chip instead.
The ICL7660CPAZ chip mentioned in the article along with the small voltage regulator are readily available from Mouser electronics.
Now, you could make up a perfboard replacement like the one shown in the article, and that's what I was prepared to do. However I happened to mention this to a friend of mine, and he was nice enough to create this for me:
http://www.oshpark.com/shared_projects/ccSnAUgE
It costs $4.80 to order 3 boards from them, with free shipping (in the U.S. anyway). My order is still pending (it's been sent for fabrication and should ship next week). All you have to do is mount the parts. With only 4 components and a few wires to solder, it's a simple project for an afternoon.
I can follow up once I get my boards and finish fixing up my radio. So far all I've done is disassemble it to get the ALC board out. I'll probably un-solder the DC-DC converter board this weekend.
-Bill, N1GPT