Enlarger is a Durst Pro I bought used several years ago. The height adjustment crank was broken when I bought it. Not a big deal, the head can be raised and lowered by hand and otherwise works great, and I got a good deal on it. But every once in a while I get the urge to see about fixing it.

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Gear A is turned by the crank and turns gear B. Gear C looks like it should engage the linear gear in the column, but it spins freely from gear B and can move in and out:

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What I just discovered tonight is there appears to be a cotter pin that is supposed to lock C in place with B, but has been sheered off:

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Wondering if anyone is familiar with these and can shed some light, maybe share pics? Thinking of heading to the hardware store to see if I can replace the pin and get this thing working.