Help with old Marlin 780

[CJW]

Hi folks. I have an old Marlin 780 bolt action .22 rifle. It is robust for a .22 and very accurate to boot. Lately I've had some light strikes that I do not think can be attributed to faulty ammunition, so I am thinking this old rifle might be due for a firing pin spring replacement.
Can someone give me some pointers, or supply some info, on how to properly disassemble the bolt and check for / replace worn parts?
Thanks.

 

[Coyote3855]

Haven't a clue about old Marlins, but I'd first try some penetrating oil in the bolt body. Could be it's just cruddy with old dried lubricant, dust, powder residue, etc. Kroil is my favorite.