This is going to be a weird answer!
After researching, this is what I found. Rochester only produced one model at there factory in Rochester NY in 1948. (Your model)
Kessler ( Made up of ex-Crosman employees) bought out Rochester and made the same rifle but called it the Kessler (Two-piece stock model).
Kessler went out of business in 1950 and Numrich arms purchased Kessler. Numrich may still have some parts on sale.
However I suggest you also do a search on "Air gun repair" on the web and locate someone near you to have it repaired.
Also see the link below
There was only one model ever produced it was the Rochester Precision. It originally cast $10 today it is worth ( depending on the condition) between $100 to $300. It was previously produced by Monroe Gasket Mfg.
There are many independent shops that repair older air rifles for a living. Do a web search for "air gun repair" and locate a shop near you to have it repaired or see the link below.
There are over a thousand different models of air rifles. Each one is different. I suggest you have a professional make the repairs. Check the web for Air gun repair and find a location that you can send the rifle to for repairs.
Precision Air was created in 1991.
There called C02 air rifles or PCP air rifles
There are shops all around the country that make a living repairing air guns and rifles that are out of warranty. In the past I've searched the web under "air gun repair" and located shops that can make the repairs.
Crosman co owns Benjamin and Sheridan. They supply parts for current and some older model Benjamin air rifles or they offer a service to locate someone who repairs older Benjamin rifles. See the link below. When it opens click on "Find a service center."
Today Crosman air gun company owns the Benjamin line of air guns. Crosman offers a free service to locate independent repair shops that work on Benjamin air guns. See the link below.
Sheridan air rifles who is owned by Crosman Sheridans are 5mm air rifles
no those are airguns. .22 bullet rifles are used in the Olympics --------------------correct answer:----------------- .177 caliber air rifles are used in the Olympics. These are high quality match air rifles.
These excellent rifles are made in Turkey.
Today Crosman Air Gun company owns the Benjamin line of airguns. Crosman offers a free service to locate independent air gun shops that repair out of warranty air guns. See the link below. http://www.crosman.com/cs/service-center