I bought a gas 1958 601 workmaster. The engine had a noise but ran good. I removed the hydraulic pump in order to determine if it was the cause for the odd engine noise. When I started the engine, a piece of the drive gear (bolted to the rear of the camshaft) for the hydraulic pump wedged and stopped the camshaft resulting in the timing gears in the front of the engine being damaged. I have read that the camshaft has been known to break from stress such as this. I removed the camshaft from the engine and inspected it. I found no visual problem with the camshaft. I would like to replace it to be on the safe side. I have been unsuccessful in locating a new cam and lifter kit for this tractor online. I can find the cam but no lifters. Do the lifters have to be replaced with the camshaft or can the old lifters be ran with a new camshaft? I determined that the tach drive was siezed and most likely caused the gear failure. Thanks.