1993 Saturn SL2 speedometer-odometer

well on the odometer the little plastic gear is probably broken drives it very common.my sisters 93 her odometer went out put a used one in it then two weeks later that one went out too.they sell the gear but u have to take the whole cluster to replace it.unless ur good at fixing things i wouldnt try it.as far as ur tach have u tried smacking ur dash while its running to see if the tach moves?if that doesnt work u would have to trace the wires to ur tach to make sure there good and if they were then would have a bad tach but u cant just get the tach ur car comes as a whole cluster assembley.let me know what u find.