Hi, I can't remember where I bought the cap but if I had to guess I would say that it had to be from one of two places, Bob's or CARS. There isn't a lot of force there, I can stop the movement with my thumb and forefinger without applying much pressure. It would seem that I either have a poorly fitting cap, worn distributor or both. I should add that the lateral movement is quite significant and it does follow the movement of the rotor. I think that the prudent solution would be to have the distributor checked, rebuilt, if necessary and the cap replaced. Thank you all for your help.