B&K PT5 Preamp/Tuner mystery volume

Have a B&K PT5 Preamp/Tuner that has suddenly developed a ghost volume. Every 20 to 30 minutes, the volume goes all the way up totally on it`s own. Max`s out at +8db. Anyone ever heard of this? I`m not sure where to take it for service in the Buffalo, NY area either.

B&K PT5 Preamp/Tuner
Krell KAV-2250 Amp
Def Tech BP7002 Speakers
Oppo BDP-93 Universal Player
this is a long shot maybe, but if you put tape over the remote receiver sensor does it still do it? if so, perhaps something in the room is emitting IR at that frequency.