Because tamping rammer machines are expensive, many independent contractors look to buy used iron from rental yard auctions. This is a high-risk game. Rental equipment is subjected to levels of neglect and abuse by inexperienced homeowners that border on criminal. If you don't know exactly what to look for, you will end up buying a very heavy, very expensive paperweight.
When I walk an auction line, I look right past the fresh coat of paint and go straight for the weak points. First, I grab the main operating handle and try to wrench it side to side. If the handle feels sloppy or loose, the rubber vibration isolators are torn, meaning the machine will beat the operator to death. Next, I pull the recoil starter slowly to feel the engine compression. If there is no resistance, the piston rings are shot—likely because a renter ran it with a dust-clogged air filter, allowing silica to score the cylinder walls.
I then look closely at the clutch bell housing. If the metal has a blue or purple tint, it means the machine was run at half-throttle for extended periods. A centrifugal clutch is designed to be run wide-open; running it at partial throttle causes the clutch shoes to constantly slip and drag, generating enough friction heat to warp the metal and destroy the clutch. Finally, I lay the machine back (always with the carburetor facing up so I don't flood the engine with oil) and inspect the shoe hardware. If the bolts holding the shoe to the lower ram are sheared or replaced with non-hardened hardware store bolts, I walk away. Buying used requires a cynical eye and a deep understanding of how these machines die.
