Compare to a known dated model, Blue Book of Gun Values.
If you are asking about air rifles it was made by Crosman Air guns.
I own one of these - they were made by FN using Mauser actions. You should see the markings from these companies on the receiver if you take off the stock.
I believe it's a Colt ( Colteer ) Semi or Bolt
Blue Book of Gun Values has a store brand chart
Both Daisy and Crosman made air guns/BB for Sears. I believe you are asking about the Crosman model 760 pump repeater Rifle. there are several variation's of the 760 starting in 1966 all the way to today. However Sears stopped selling gun in 1980 so yours is before 1980. I would think yours would be closer to the 1960 date because the later sears model 760 carried a model number of 126.19331.go to http://www.pyramydair.com/ and do a search for 760 to see if this rifle looks similar to your rifle.
IIRC Mossberg. No sn data available. - I own one of these, they were made by FN using Mauser actions. The markings are on the receiver under the stock. Mine does not have a serial number, from the info I could find on when Mauser made that type of action (Sako trigger, sliding safety) my guess is it was made in the 1950s.
Standard Catalog of Firearms or the Blue Book of Values might help
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)
The Hawthorne Warrior M825 .22 LR was sold by Montgomery Wards in 1957 and 1958. It is actually a Mossberg Model 140 rifle.
1,000 in mint condition. They are a rare rifle. Less than 5% of 760 BDL's were left handed.
50-100 or so