Just got an 89 American standard Tele black with maple neck. In excellent shape except three way switch and tone controls are a little sticky. Also, unpluging from input jack seems a little to tight. Remove control plate and observed white powder like sandings from body filler or maybe clear coat inside. Looks like some stuck on blade switch. I was told this guitar was played for two years in lessons and has sat in its case for the last 20 years. Any info would be greatly appreciated. Also, what should I clean controls with that won't damage guitars finish.