Yes, the black sync switches on the head blocks are prone to shorts. Cuts the signal right down to nada in some cases. It's really a drag to sit there wildly clicking a bad one back & forth to get it to kick in.
I recently finished transferring my entire tape archive of multitrack tape work from the mid 60's to the mid 90's to Nuendo. Including my early early 70's 3340 stuff...which luckily consisted of songs that had reels and reels of unmixed slave four track reels that I didn't erase during the submix process between two machines.
I'm pretty excited to have kept the early stereo/mon and 4-track multitrack things on separate reels. I've flown them all in to Nuendo and can now nudge the individual song tracks from the various reels back and forth to sync, clean them up and then remix and remaster the old stuff again. This time, without the inane submixing that constantly had to be done between two machines in the early days.
Now that everything is transferred and accounted for, I realize I'll probably never use that 3340 again. I thought for a minute about selling it, but I think I'll just keep it around like all the other Tascam stuff around here.
I thought my kids might be a little interested, but, teens that they are, they're pretty much into computer daw recording and video editing stuff...they sort of snicker when they take a look at the analog recorders..."what?..you mean I have to WAIT for the tape to rewind before I can add the next idea? No thanks Dad."