Well I do have a good Yamaha KXW 421 and it works very well, no problems.
Also have a Pioneer 404R, no problems, a Marantz horizontal deck with too
slow reverse, a dead Kenwood 6050, a dead B & O Beocenter 4600 deck and a
very good Kenwood 4080 which has a reverse which squeaks for a few seconds
at the end before stopping. These are good commercial decks, not
Nakamichis. They do not reccomend any tapes longer than C90 to be used in
any of them, thats logical as C120s are too thin and do stretch a bit too
much causing entanglement in any deck whether a cheap Pioneer or a
Nakamichi. Just use more C60s will be your safe bet. This means 2 C60s for
one C120. Try this first before sinking further into repair woes. Cheers.