Reassembling my Longines 30L, I was expecting a nice high, and steady amplitude. My other Longines all behaved perfectly! All the checks were passed, barrel+arbor, gear train, pallets, balance etc - all look good, yet it's barely running 😟 I thought I'd put a bigger lens on the microscope and have a look at the balance pivots. The top looks like it could do with a clean. I know that pivots are sometimes flatter to reduce the difference between horizontal and vertical running,  but