intermittant loud pops from my 7 year old eros phono

[Jay]

My stock Eros 1 has served me well since early 2016, but in recent weeks has begun to have intermittent pops on the right channel only. The "pops" occur whether a record is playing or not.  It will do fine for several minutes up to an hour, but then there will be a brief spate of three or four loud pops a few seconds apart, then all is well again for a while.  I thought it might be my stereomour II, but now I have a BeePre/Kaiju, and the intermittent pops persist.  (The Stereomour is now in my computer room sounding great through an old pair of Yamaha NS-670s)

My plan is to work my way back from the right speaker terminal chopsticking and reflowing solder joints.

I have tried to pull the tubes to clean the pins, but they seem to be stuck and I'm scared to pull too hard.  Is it OK to put a drop of contact cleaner in the socket to try to free them up?

I know that solder joints are the most likely culprit, but could this be a bad tube?

Thanks for any suggestions on where to focus or any other guidance.

[Doc B.]

The fact that the tubes are hard to remove could indicate that the sockets and tube pins have oxidized enough to stick together. So yes, put a little contact cleaner in each socket terminal. Then gently rock the tube back and forth a bit to work it up out of the socket. Gently is the key word here. You don't want to use so much force that the tube cracks.

[Jay]

Follow up: The tube pins were clean, and switching tubes around had no effect. I pulled the right channel circuit board up and reflowed everything I could reach. In some places the solder had not flowed through holes all the way. I also resoldered the input and output jacks.  So far after 3 or 4 weeks, not a single pop.  It's always the solder joints!