[GreenKeys] Model 33ASR troubles

[Andreas, Steven Robert]

So, I'm having troubles with my 33ASR.
Known problems:
1-Something (a relay near the back-left I think) buzzes loudly while the set is plugged in, but not turned on (i.e. the knob is in 'OFF' position)
2-The teletype chatters and types random gibberish in 'LOCAL' mode
(The above two occurred simultaneously between power-ons, weeks after I recieved it.)
3-The tape-reader has the least-significant bit stuck high. Usually.
4-The tape-reader will not start from the switch, however, it will run if I manually press down the solenoid in the back-right of the machine.
(These have been present since I got the machine)
1 and 2 I'm not too worried about -- I mostly would use the machine connected to some sort of computer anyway -- and I think 4 has something to do with an aftermarket board installed that is installed in series with the circuit that controls the activation solenoid. It's No. 3 that's really puzzling me. The least significant bit will seem to become 'stuck' -- i.e. usually the bit will be transmitted out the serial as a 'mark' even if there is no hole on the tape. I have made sure it is not an issue with the mechanics of the tape reader; I have verified its function using an oscilloscope, and the problem occurs even if the wire corresponding to that bit is disconnected from the rest of the machine at plug 6.
The problem seems intermittent; I can't figure out why it sometimes happens and sometimes not.
Is this a problem anyone has encountered before? I have to say it has me completely baffled. I don't think it's a problem with the distributor or in my current loop-serial converter; the keyboard and printer (and tape punch) both work fine.
I will say that I have very little knowledge of teletypes, I mostly concentrate on old computers and have acquired this TTY part of that.

Thanks!

Steven Andreas

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