my 1 used to do that , i used it for my speeedometer when it got shakinid either slow it back untill it didnt wich was about 72 perfect or run her up a bit kick the cobbwebs out ckecked about every thing took it to the tire shop they thru it on the balancer was good untill i told him crank her up the whole machine was shaking like it was gonna come apart thru on a new set of tires ballanced gone slipped belt in the tire prob from doing whole shots lost a wheel wieght 1nce too but solved what ended up being a cheaper 1 was time for tires anyways