A friend gave me a PL-500, but I don't know anything about it, nor have I even tried it out. Not much here on AK for that specific model, but others in the 5XX series get some chatter. Needs cleaning after many years of non-use, but looks complete. The cover is scratched up, but not cracked that I can see. What should I know about this model what maintenance should I expect to do to have it perform at it's best? Thanks, Mike.