Intermittent Power Loss

Another problem I'm having with my vintage Model 10s is an intermittent drop in volume (power loss?) in both left and right speakers, not at the same time. Could be the left one time, could be the right. I've tried spraying contact cleaner at the terminal posts on the speakers and my amp. Helps for a while and the starts in again. Any ideas?
Comments
If it is happening on both channels, even if at different times, it is likely the amp.
If you have another pair of speakers, play them at the same volume level to see if they cut out, too. If so, it is your amp.
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk
In that case you don't have a polyswitch. Try cleaning the fuse ends and clip holders...as in take the fuse out of the clips to clean it all.
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk