Call Marlin and get them to send you a parts and price list for the 336 series. They will also send you an owner's manual with details about take down as well as an exploded view of the gun. This will come in handy if you need future parts. The number is 1-800-544-8892.
They will likely send the stuff in advance and ask that you send a couple of bucks to cover printing and shipping. It's well worth the cash.
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Guyon
NRA, GOA, & TFA Member
Protect your RTBA!!!