Amp repair...What to expect.

anywhere from 300-500 hours to break-in.

It's not break-in it's parameter settling of mainly large signal components such as power transistors and it's not 3 months worth of listening. It's substantially shorter at least audibly. 25...50 hours is more realistic.
Leaving unit on stand-by for a few days will also do the trick.

Mine took 50 hrs. to start sounding like a Sunfire again. Then at about 300 hours, it opened up and sounded like its old self (except that now it was dead-quiet).

I like the DYI spirit in several of the posts.

Just last month I got tired of dropouts on my two Sherbourn 5/1500A monoblock construction amps, chatted with a friendly tech, ordered $2.50 relays, and using my Xtronic solder gun and air tool workstation, some desoldering wick, and high silver content solder, i replaced all 10 relays.

In the process i removed all connector harnesses and applied electrical contact paste to these and the terminals, dusted the heatsinks.

I have been making sweet eyes at Pass Labs and Classé monoblocks for a while, but the 4 of them would be hard to justify (CP-700 biamps) now with perfect Sherbourns.

To Marakanetz and other Sunfire owners...

This is an interesting find, but price is too high:

http://www.ebay.com/itm/281100878773?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2648