www.mac1airgun.com ).
The
valve stem seal on the Mark pistols is not a removable o-ring seal. When this seal needs replacing it’s usually best to send the stem to someone with the equipment to do the work. It is not something the average airgunner would tackle.
Basic Mark Pistol Disassembly 1 – Remove grip screws, grip panels, and piercing assembly.
2 – Loosen rear sight windage adjustment screws (140-9).
3 – Remove rear sight screw (10-18) while holding pistol upright.
4 – Hold pistol upright and remove rear sight blade (10-17).
5 – Old Marks have a set screw under sight blade that is removed next (10-14).
6 – Carefully remove detent spring (10-15) and detent ball from hole (10-13).
7 – Remove elevation screw (10-19) and elevation washer (10-40).
8 – Old Marks have bolt guide screws that are removed next (10-64).
9 – Carefully pull bolt guide assembly (10-61) out back of frame.
10 - Remove barrel nut (10-4) at muzzle. Use spanner or needle-nose pliers.
11 – Slide barrel housing (10-2) out of frame.
12 – Loosen barrel set screw (10-6) located on top of front section of receiver.
13 – Remove barrel nut at breech (10-5).
14 – Slide barrel out of frame.
15 – Slide hammer spring (10-23) out of hammer (10-22).
16 – Remove cocking knob end (10-59) and shank (10-21) from frame.
17 – Slide hammer (10-22) and hammer sleeve (10-24) out of frame.
18 – Remove trigger guard screw (10-66) and trigger guard pin (10-44).
19 – Remove trigger guard (10-12).
20 – Remove trigger spring (10-34).
21 – Drift out trigger pin (10-32).
22 – Remove trigger (10-33) and sear (10-33).
23 – Remove valve screws (10-26) from side of frame.
24 – Pry valve (10-25) from frame using large slotted screwdriver in valve slot.
25 – Valve will pop out with stem (10-67) and valve spring (13-29).
Notes: To create leverage for valve removal, I use an old screwdriver handle or wood dowel as a fulcrum.
Valve body seal (600-28) often sticks to frame and valve.
If seal sticks to valve body, it is sometimes necessary to carefully polish off stuck pieces using 0000 steel wool.
There is usually no need to remove the safety assembly.
Button Piercer Disassembly 1 – Use small slotted screwdriver or dental pick to carefully pry star washer out of cap.
2 – Slide thick washer out of piercing cap.
3 – Inner o-ring seal can be seen at base of piercing pin.
4 - Carefully remove inner seal with probe, xacto knife or dental pick.
5 – Replace piercing pin seal (600-84) with new o-ring seal.
6 – Replace piercing body seal if necessary (150-54).
Notes: Piercing pin seal (600-84) will usually be damaged during removal so do not remove unless leaking.
It is not necessary to completely disassemble all piercing assembly parts for seal replacement.
