Tuning Winchester 1977XS already broken!

Yeah, it's a cheap multipumper, but it's my only pellet rifle currently. Has less than 1,000 shots through it and it's already broken. Is it worth it to send this thing in for warranty repair? Or should I try to fix it myself?

When I try to pump it, the air escapes from the piston somewhere. I can hear it hissing on the compression stroke and almost nothing goes into the gun. It's probably a simple seal or something, but where do I get parts?

I hesitate to send it in for warranty work since it'll probably cost half of what I paid for the gun (60 bucks) and I don't have a receipt for it. I think I bought it at a Wal-Mart.
 
At the very least, you could try lubricating the pump seal and saturating the felt oiling washer behind the seal with Crosman pelgun oil. It comes in a smallmwhite plastic squeeze tube in a blister pack. Are the seals dry? These pumpers need regular oiling. You need to be sure some drops of oil also get down inside the pump compression tube to lubricate the check valve seal. All it takes is one piece of grit to hold the check valve open.
 
I got my Winnie 1977XS from Academy. They didn't include a manual w/ it. I had to download one from PA. Oil the felt wiper w/ some non detergent 30W and let it sit awhile. Good luck.

Quote from Page 9 of the manual:

PROPER CARE
To maintain top shooting performance, lightly oil the three pumping lever hinges and the felt wiper on the piston every 1,000 shots (No. 11). Use a 10-, 20- or 30-weight non-detergent, automotive motor oil. DO NOT use light, household type oils or aerosol type spray lubricants since they may contain substances or additives.
 
Don't throw away that Win1977!! It's not very difficult to work on and should be easy to repair as long as nothing catastrophic happened. I have a couple of these and think these are awesome in power and accuracy. I'd be glad to help you figure out what's wrong with it. Heck if you were close enough to me I'd work on it for free just because there's something to be learned. For now it sounds like maybe the piston o-ring seals need to be replaced. If this is the cause, then you can call the Daisy customer service line at 479-636-1200 to order a new set of seals for either the Daisy 880 or Winchester 77 (I'm not sure if they are carrying spare parts for the 1977XS, but I believe the seals for these models are all interchangeable). 
 
I forgot to mention that there's a guy on Youtube (Daisy 880 Fanatic Fix It) with videos that show how to replace the o-rings with ones that are available from your local big box hardware store. For the piston head and pressure tube, the o-ring used is a Danko #11 IIRC, and he mentions another for inside the valve body assembly where the valve poppet is located. Maybe this will be helpful.

I have pics of my disassembled Win 1977 and Daisy 880 if that helps. I'm new to AG Nation forum so not sure if I'm allowed to post pics without more posts.
 
I forgot to mention that there's a guy on Youtube (Daisy 880 Fanatic Fix It) with videos that show how to replace the o-rings with ones that are available from your local big box hardware store. For the piston head and pressure tube, the o-ring used is a Danko #11 IIRC, and he mentions another for inside the valve body assembly where the valve poppet is located. Maybe this will be helpful.

I have pics of my disassembled Win 1977 and Daisy 880 if that helps. I'm new to AG Nation forum so not sure if I'm allowed to post pics without more posts.

I like his vids too. They were very helpful when I modded the trigger of my Winnie. I also did the silicone caulk in the buttstock fix and closed off the BB hole by using a rectangular piece of sliced ear plug foam epoxied to the hole. I also put my Barska 4X32AO w/ mil dots on it instead of using the 4X scope it came w/. Lastly, I put an LDC from Geo Schoomaker on it to quiet it down and to steady the barrel in lieu of the duct tape barrel fix.

Recently, I ordered a few thousand 7.87 gr wadcutter/flatheads for it from Daisy. I'm good to go for quite awhile w/ it.
 
Probably a good lesson even though it hurts the wallet a little... It pays to buy better quality where replacement parts can be had !! Winchester does not make those, they only pay some mfgr to stamp there name on it. Years back I was involved in an insurance claim for a customer, the Ruger gun was never made or even acknowledged by Ruger, from what I learned, the manufacturing company paid Ruger a fee to use their name on a cheap rifle for a short period of time, then went out of business....lesson learned !!!!