See the link below.
You did not state what is wrong with your rifle so it is not easy to give you any advise. I suggest that you go online and do a search for "Air gun repair" and find a shop near you that can do authorized repairs. OR go to ( SEE THE LINK BELOW.) and find the manual for your air rifle.
It all depends on what is wrong with it.
I hate to answer a question with a question but, can you be more specific?
I am not familiar with this particular model (427) but I am familiar with Benjamin air rifle. If your problem is that there is on Scope rail to mount your scope then I know how to fix it. Crosman airguns owns Benjamin air guns. Crosman offers a special Benjamin barrel clamp that lets you mount a scope to it. See the link below
Your question is two parts. So I'll do my best to answer it. Both Crosman and Daisy made airguns for Sears under the JC Higgins brand name. All Crosman airguns carried the model 126.????? and Daisy models started with 799.?????. So yours was made by Crosman airgun company. "Bluebook of Airguns" carries a cross reference that list the REAL model number of the Sears airguns. Unfortunately not all the numbers are known, and I can not find a reference to 126.1980 in the crossover. Crosman offers a service to locate repair shops that fix older Crosman airguns, But you need to have the Crosman model number to use it. (See the link Below) Crosman also has a web page that list "MOST" all of their owners manuals and parts manuals. ( See #2 Link below) So here is what you can do. Go through the manuals and locate your air rifle, then you will know what model it is. Then use the Crosman locater to have it repaired. As far as price. I need the model number to set an estimate of value.
It depends on the model and what is wrong with it.
It all depends on what is wrong with it.......BTW its a rifle not a gun See the link below for the parts manual.
These guns were notorious leakers. Today Crosman owns the Hahn 45 model air pistol. Crosman offers a free service to locate shops that repair o0lder Crosman models including the hahn 45. See the link below It's also known as the Crosman model 36 frontier.
I would have it looked at by a compitent gunsmith.
Depends on what is wrong with it. You did not say.
Crosman has both the owners manual and parts manual online. See the link below and download your 760 parts manual. Then contact Crosman customer service and order the parts. Everything is on the opening home page for Crosman at the bottom of the page.
If it's still under warranty I would send it back to Crosman or at least contact customer service at Crosman. WWW.Crosman.com