Jolida 1000RC Tube ???

You might have had a poor contact on a critical contact on the tube pins and the socket, but your description is also consistent with a shorted tube also. Check the bias on that tube. If it is still showing proper bias then every thing is probably well. If not you may have a damaged resistor in the bias circuit. FWIW the KT77's were discussed at some length on AA tubes forum. It seems that there have been a lot of them with undersized pins - you might do a little research on this forum for the background on this problem.

Chgolatin2
As newbee mentioned, you are probably safe at this point as long as you are able to measure a bias within the indicated range (40mV +/- 5). If there was a problem within the amp, you would not be "working fine now". If you took out a cathode resistor or bias resistor, you would either have one tube with no bias reading or you would blow a fuse within 30 seconds of powering up the amp.

My guess is there may have been an arc due to the potential undersized pins of the JJ KT77 tubes. It has been a common problem. I would recommend you get yourself a small plastic "pick" and go through all your tube sockets and pinching the metal contacts. This will help in making a better contact with the tube pins.

Thanks for the advise!