[Frameworks] Steenbeck ST928 - polygon prism seized

[Jean-Pierre Marchant]

Hello all,

I have an 8 plate Steenbeck in my home studio which has 2 screens. Overall
it works ok but it's got one big problem: the left hand polygon lens does
not want to turn at all. The right polygon lens works fine. I would like to
get the left one to work so that I can run a picture film through it with
sound.

Something details I've noticed:
1) as expected, when the machine is powered up the right polygon spins
forward and backward by toggling the clutch/brake switch next to the speed
control lever. I've noticed that when the clutch/brake switch is ON, I
can't move the right polygon at all...it is seized up - as it should be.
However, when it is in OFF, I can move the polygon by using my finger - ie
it spins freely.
2) The left polygon seems to be stuck all the time whether its switch is in
ON or OFF. When I toggle the clutch/brake switch for it I can hear the
clicking sound of a relay and something does appear to move slightly on the
motor shaft for that polygon (I've looked at it by taking off the panels
and looking underneath).
4) So I'm guessing that it's either a mechanical issue that has seized up
the gears, or it's an electrical issue preventing the gear shaft from
releasing for that left side polygon.

I've checked my relays and fuses and they appear to be ok - I tested some
with a multimeter, and for others I swapped around similar relays and
everything is still the same. The belt for the polygon shaft looks like it
is on properly and in 'ok' shape, if a bit oily and dirty.

Does anyone have any advice or any idea what the problem could be? Any
help/advice would be welcome.

Sincerely,

JP Marchant
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