Rotor arm problem
 

My Rotor arm on my distributor is no sitting tight it’s got s bit of movement and when trying to start the car it’s hitting the distributor cap and makeing it come loose,the engine is a 914-6 engine ,I bought a new arm but it to seems to be loose on the shaft and working the cap loose ,any ideas what I can do
Brian

Should be just a vw bug rotor, 70s style.

Sure it’s the rotor and not the shaft? With the rotor removed, see if you can move the shaft back and forth (side to side) with your fingers.