I had the jumping tach needle problem for over a year, which developed into an intermittent ignition problem...misfiring etc. I replaced the ignition coil and the problem went away. The engine runs smoothly and the tach is steady. However, when I changed the coil I took the distributor cap off - it's mounted directly above the coil and is in the way. There was oil in the distributor, and quite a bit of oil that made its way out of the distributor and over everything underneath it. I see in the Helms manual that there is an o-ring on the distributor shaft. I'm hoping that all I need to do is get the o-ring replaced.