I took in my Sony ES 555 receiver to the authorized repair shop, to repair the motorized volume knob which no longer moved via remote control. (first time and it is 4 years old)

Anyway they fixed it under warranty.

When I went to pick it up... I noticed that their was white goop around the power transistors that are screwed to the Heat sink. It was kind of messily applied, and find it hard to believe it was there when I dropped it off.

So I came to one of the 3 conclusions:
1. I am imagining the white stuff not being there before.
2. They applied the white stuff free of charge to improve the performance of the transistors.
3. I have been taken advantage of and they removed my ES quality transistors and replaced them with lower grade parts.

I will post a reply tommorow after I give it a carefull listen.

Have any of you ever heard of part swapping when you or anyone else has taken a unit to be serviced??