Crosman has some parts available online. See the link below for all the Crosman rifle parts manuals and owners manuals. You can order parts from Crosman.
The CROSMAN 760 Powermaster started production in 1966 then went through 8 different changes and ended in 1991
You need to state what condition it's in. without more information it is not possible to answer you.
There are several versions of this model. Here is the web page for all of Crosman air guns. Owners Manuals and Schematics. See the link below.
It all depends on the current condition of the rifle. You have not given description so it is not possible to give an estimate of value
The Remington Airmaster is rated at 725 FPS (Feet Per Second). The Crosman 760 Powermaster is rated at 595 FPS and the 760P is rated at 600 FPS. 10 pumps each.
You have two choices. First: Crosman has the parts manuals online along with the owners manuals. (See the links below) there are several versions of the 760 so look at each one to find yours. Then contact Crosman for the parts you need if they are available. (Customer contact.) Second: If you have no luck with that, Crosman offers a free service to locate shops that repair old Crosman products. So see the 3 links below.
There are well over 8 different variations of the Crosman model 760. Unfortunately Crosman doesn't have an on-line list of dates for model 760. However each model variation has a distinct variation that can give you a hint of the year it was made. So here is what I suggest. you can try Crosman Customer Service ( see the link below) and ask them, or you can get a hold of a book called "Bluebook of airguns" and read the section on the model 760 and identify your model year.
The Crosman 760 doesn't shoot Bullets it shoots BB's or .177 caliber Pellets.
There are several versions of the 760. See the link below for all of the crosman models with dates and manuals.
Crosman has made 5 or 6 versions of the 760 and has parts available (See the link below for the older 760 parts list. ) I would contact Crosman Customer service to order the parts (see the Link below)
Serial number 36822