Just picked up a 1930's Ritter dental air compressor (tag is missing so not sure what model, but looks like a Model F or B from pictures) in near perfect shape (would you believe it was only $40?) and I was wondering if anyone had any info on it. I'd like to change the oil and I was wondering what kind it takes, and I am planning on using it to pump up bicycle tires in my garage so I need to know about what the max psi I can make is. I'm hoping I can get it to about 50-60 psi. I was also wondering if anyone happened to have a spare pressure gauge from the 30's. The one on this is wildly inaccurate and needs to be replaced.