I wrote a review of the PP70 on this site. The machines are probably not that different.
Watch for interior air line leaks. I replaced mine with nylon truck air brake lines and compression fittings. But if you don't hear any hissing leave well enough alone.
I'm using the Harbor Freight 3 foot long desiccant air dryer for around $40. The smaller inline ones seem to plug up the air flow. The shop's main compressor has a water trap and one should be included with your PP50 that attaches on the back if it is like the PP70. Others may know more about the PP50.