Re-capping A 15 Year Old Solid State Amp

I'm considering buying a pair of Krell FPB 750mcx monoblocks in the next 12 months. These amps are 15 years old. What type of behavior do old solid state amps exhibit when they need to be re-capped? Is there anything else that should be refurbished besides the caps in older solid state amps?
AFAIK only electrolytic caps and possibly switches if you have problems with them. Everything else should last your lifetime. Old dry caps have high ESR (Equivalent Series Resistance) increasing output impedance of the amp. It will take away some dynamics and will make a woolly bass - at least that's what I observed when I changed power supply caps in my older SS amp. Whole thing started sounding much more dynamic with better bass definition.
1. 15 years isn't old if it had been always used and i'd probably give it another 5...10 years safe.
2. Amp in need of recap may increase noise level when in idle or even start humming for no reason.
3. You may do visual inspection on how clean the caps look and how clean the PC board where they're connected and if you spot traces of heat or liquid, it's another sign.
I won't buy a 15 year old amp as its history!!
Let me know when you have your old amp on curbside.
Ebm - In your statement "I won't buy a 15 year old amp as its history!!" all I can say is you must be buying throw-away junk!!. I have owned many Solid State and Tube amps much older than that from reputable companies (ARC, Conrad-Johnson, McCormack, Bryston, etc.) who use high grade components and there is no problem.
Sorry jump on a 15 year old amp ASAP!!!!!!
I am not implying that one should purposely buy an amp 15 years old or older, but I am saying that I don't think they should be afraid to either, if it is made of quality components. There is no reason to be afraid of an amp that was not manufactured on or after the year 2000 because it is now 15 years old. That is all I am saying and I apologize if it was misinterpreted.
These Krell FPB series amps ran class A, very HOT. This is one reason I never went Krell. These amps burn up overtime. Having said that, they would be a incredible bargain in todays hi cost, hi-end audio world we have today. So, I say FIX'em if you can. Regards,

Matt M
Having the original service manual and the spec on the parts would be the only way this would work. Otherwise, you are at risk for a bad outcome.
15 years old is nothing. I have electronic gear built by Tektronix and HP (the real instrument company before they became a PC printer company) that was built in the late 60's and 70's that still meets original specs today.

I also have a recently re-furbed Spectral DMC-10 phono preamp from the mid-80s that sounds just wonderful. I did re-cap this and rebuilt the PS.

With a power amp, the number of hours on it will have an impact due to the heat, as heat is a killer of electronic devices. If it sat off for many years, this is better than someone running the amp 24/7. Unlike what some will tell you, running the gear 24/7 is not the best for the components. There is also a possibility that voltage transients from power line surges can weaken components like bridge diodes and perhaps power transistors. Sometimes you will hear "pop-corn" noise or hum from the input stages (the input transistors). If there are no hum problems or noise, the amp may be in fine shape.

Regarding re-capping, be sure you can get replacement caps in the configuration you need them in. Some older gear used electrolytic caps that were "twist lock" style that are virtually un-obtanium these days. The computer grade electrolytics that have screw terminals may also be difficult to find. This may mean custom kluging to get a modern Panasonic cap to fit a board with screw terminals. A good example is Parasound HA 2200ii which used screw terminal PS caps, which are difficult to find except though Parasound (read EXPENSIVE). So you need to take a good look inside the amps before you commit, and then do some research on the replacements.

And, if you think you can find the older caps on EBay, you may but they will be just as old as the ones you have in the first place. If you can, use upgraded commercial grade (105 C rating) electrolytics for the replacements.