I have an older air compressor which I bought new and over the years abused with air tools etc. (The tank is 30-35 gallon and in great shape) the tank does not build pressure currently. I am thinking the rings are shot. The oil less type compressor has been noisy the last two years and now does run but no pressure about 10 PSI etc. The model 919-152921 with a pump no AC-0059. How much are the rings etc. and how difficult will it be to put them in provided I am going down the right path here. If it’s on the cheap and fairly easy I will add the rings but if expensive and labor intense then scrap and step up to a 60 gallon tank.
Quick Background:

I am a computer programmer for my real job and on the side hobby I restore older 60's Mustang converts. (I only state this not to boast but assure you I can weld, rebuild engines and replace front ends etc. etc. and can wire with electric.)
Any thoughts on price and toss it or keep it are welcomed! :-)

10Psi That is very low
as regards The Piston Ring (seems to be only 1 on this model priced about $6
From Sears Parts Direct

I have found a recent posting elsewhere which will point you to where they stock the rings and had advice on how these are fitted
www.selfhelpforums.com/showthread.php?t=15593
And very low compression Indicates a Leak else where . blowing Gasket? Remedy when rebuilding Buy a tube of non setting Liquid gasket (can be wiped off) and Torque the Barrel down

PS I Have an ancient compressor (no tank) which the Ring and crank are Destroyed yet it still Pumps Tires up to 35 psi