Just purchased a new PC7336 at Lowe's. I'm a newbie. I've been reading alot of posts here and i'm trying to figure out what couterweight i need and what size pads i should use. Does the size of the pad determine which counterweight i need? Also does the size of the pad determines which backing plate to use? I'm gonna practice on a old hood from a friends body shop before i try it on my car, or try it on the older ambulance at work. Replies greatly appreciated. Thanks.