If the possibility of bad heads arises, you luckily have a few spare sets lying around! Can the heads just be changed out? I wonder as I had a very old Quasar video tape player (it took some oddball coaxial cartridge, so this is very pre-VHS) and all you had to do was lift the top, twist off a knurled hold down, and the video head drum was free!
Hey! Just thought I'd check before I posted and Labguy has one of these! He's excited about the ez-clean heads too!
http://www.labguysworld.com/Quasar_VR-1000.htm
Another memory of this thing just strikes me-it had a dehumidifier built into it! I guess if you thought your tapes were a bit damp (?) you hit this switch on the front and a very LOUD fan would kick on.