Velodyne FSR-18 ramdom speaker pop

I am the second owner of this incredible sub and have enjoyed it for sometime now but it has started to make a rather loud random popping sound emanating from the speaker. I can have the sub set to auto power mode or powered on 24/7 or powered off for 24 hours then turn it on and the popping will commence for about a minute stop then a few moments later the popping will startup again and pop two or three times stop for a time while I’m watching a movie or listen to music and start up again or just as it’s sitting with no single going to the amp, interconnects disconnected.
This is what I have tried to resolve the problem
1) Auto power mode, on
2) Power 24/7
3) Power off for 24 hr then on
4) Interconnects on attached to both terminals
5) Interconnects on attached on to one terminal
6) Interconnects detached from both terminals
7) AC power cord plugged into grounded receptacle
8) AC power cord plugged into Monster AVS 2000 power conditioner
9) AC power cord plugged into Monster HTPS 7000 power conditioner
10) AC power cord plugged into a non grounded adapter
Has anyone experienced a problem like this, to me it sounds like a capacitor is starting to go in the amp but that is just a guess.
I would hate to send the subs amp to Velodyne and get charged $250 or more for just a component replacement.
If anyone has any tech info on the amp or knows what would fix the problem let me know.
Own the same sub-use it in the auto/on mode have--never--
heard a pop at any time coming from it--close friend has the same model-his completely died-was the amp-company
repaired-for resonable price--good luck.