WOW, the RT-909 is amazing!

Poor design? Definitely not. In need of some love after 40 years? Probably.

ChopperChas said: ↑

…The 707’s are *extremely* finicky about the quality of the pinch roller and the alignment of the guides. Even the tiniest of tweaks in the right side guide causes the tape to skew, and the metal is so thin that it’s VERY easy to tweak the guides. Dirty pinch roller greatly affects tape skew as well. It’s just not an ideal design…

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Pinch roller pressure and reel torque settings are suspect here. Old, dried out pinch rollers are also possible. This is one of the most reliable and robust transports in the Pioneer R2R line, when properly restored. RT-707s will play tapes that the RT-909s cannot handle (wrinkled, sticky, etc.).

Excessive reel take-up torque will pull tape off of the pinch roller, one direction or the other. Excessive back torque will also cause similar problems.

ChopperChas said: ↑

Oh… so, neither of the bias/eq buttons seem to make one lick of difference when recording. Is that normal? …

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First possibility is that the named switches are dirty/corroded and could benefit from some DeOxit. To verify, actuate each switch at least 100 times, and see if you see a difference in performance. If so, DeOxit is your friend.

Next, you may be using a tape that requires more bias than the deck is calibrated to deliver. Normally, the deck should be calibrated using LH tape (std. no longer available anyway). New tape, produced today (such as RMG LPR35), does take a bit more bias current to get good frequency response. The two tape types are not separately calibrated, as in cassette decks, so it is not possible to calibrate both settings to be the same. The deck is calibrated to LH tape, and the STD tape settings simply adjust downward by switching components in and out.

Your playback EQ may be calibrated too bright for your record to compensate for. This calibration should be done before record calibration is performed.

Good luck,
Rich P