Hello, I've got a 2002 Manitou MSI30D in quite good condition, less than 4000 hours, however it drives terribly - it lurches until up about 50% speed. Over 50% of max speed it runs smoothly - and very fast. If lifted off the ground, the wheels speed up and slow down smoothly - but under load, it's a different matter.

It's like a feedback problem in a governor that's overcompensating/hunting. Anyone else experienced this issue, or know what it is/how to fix it? It arrived like this - and having purchased at auction, we have no idea of it's history.