ok here is the pic of the one that was on it i have replaced it with one identical to this! see the lil indent on the back should an o ring go in there? or could it be the o ring on the oil line is flattend out which i think it was?
See if any of these help.
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Mine had an 'O' ring behind the brass flange of the oil pickup tube. It was 'mushed' so I replaced it.
Your crankcase signal port is much larger than the one on mine. I used a 1/16" drill bit shank to line up the port before tightening the two mounting screws.
The only gasket I had to make was one for over the diaphram. there wasn't one on it to begin with and that's where it leaked. You got one?
You got the little foam dounut oil filter?
I used a hand paper punch to nibble out the large hole and a multi-size leather punch to make the little holes for the screws and signal port.