Loud pop and "Left Fault"

My 8-10 year old BAT 300x SE produces a loud pop occasionally upon start after the unit goes thru its warm up cycle for the tubes (about 60 seconds by design) .  If  the volume is turned down after use, powered down, and then restarted later in the day or week, and left on for 10 minutes there is no pop.  I am assuming this is likely a dried up capacitor issue.  Ultimately the unit will probably need to be sent back to BAT for repair however I thought it best to check here for some insights worthy of exploration Prior to contacting .  Many thanks for your thoughts.