Obviously the metal washers look terrible. Even the clear washers look out of place a lot of times. I prefer the full plastic protector because it provides the most protection, looks the best and also helps bring more of the GI light out from under the plastic. Generally I try to get a full set of protectors and install them under any that look like they would be easy to break. A lot of the sets are overkill and not all of the protectors are worth the time to install if the plastic is in a spot or shape that would be hard to break. That said, I absolutely HATE the colored plastic protectors. Why would someone want to make their entire game look puke green instead of the intended colors in the artwork?
Quoted from ForceFlow:
Protectors/washers should be placed between the top of the plastic post and the nut of the metal post. Not just slipped on top of the metal post and the plastic put on to of that.
I'm going to have to throw the BS flag on this one. This is not the way to install them. You might get away with this on washers, but not on plastic protectors. A lot of games have very little clearance between standup targets or even the sling kickers and the bottom of the plastics. The first time you hit one of these stand ups, the target face will bend back, get stuck on the lower plastic and not have room above to come back forward resulting in a stuck switch. I have seen this happen on a few games. Also, installed like that you will have a couple of less threads of screw into the playfield making the post less solid and more prone to bending and breaking. I always install the protectors as they were intended, between the top of the post nut and the bottom of the plastic. This has the added benefit on older games of helping flatten warped plastics and most likely will help prevent plastics on newer games from warping in the first place.