Is this one of the West Bend sourced motors or a Wiz-badged Scotty? You reference both air & water cooling so I’m guessing a WB? I’ve had no end of trouble with that era Walbro and the drain and Remora-like high speed needle protuberance – they all leak like a seive. They only used the Walbros for a year or two then went back to the Tillotson MD, there must have been a reason….. I don’t think any of the ones I’ve had still had the spring – given the propensity for leakage, it must have been lost by prior owners years before I got ahold of them!
Thanks to EdgarTC for a possible reason for the spring – I hadn’t considered that!