The year old amp ran fine. It was upgraded and ran about 20 hours off/on for 4/5 hour sessions then started to distort. It also ran hot and volume level dropped after the Milflex copper caps were added. It did sound good to me until the distortion started.
I opened it up and the 6.8k 2 watt resistor was torched. Two of the Milfex are leaking a little oil. One formed a finger point size pool of oil on the base plate. The damaged resistor is now reading over 10k so needs replaced. Will have to be ordered.
My question is what caused this? Any ideas?

Thanks
John