Bostitch BT200 cleaning & repairing

Here are some photos and information I compiled while stripping and repairing my Bostitch BT200. I didn't find this information anywhere else, which is surprising since I own 6 of these and have found them to be somewhat prone to the diaphragm blowing out of its seating, and breakage of the firing pin.

NOTE: when the gun will not fire a nail, but instead releases pressure around the trigger area, chances are the diaphragm has become unseated or was incorrectly installed. See disassembling and reassembling frame cap below.

NOTE 2: This information is provided only to show you how I disassemble and reassemble my own tools. This is not intended to encourage any such behavior on your part. Any repair or modification to power tools can be dangerous to your health.

Replacement parts can be found online.
(Good luck, though, with the Bostitch online store. When I ordered, their website showed inventory for the parts, and charged my credit card, promising delivery in a few days. Weeks later I called to find out that only a few parts had been shipped - to the wrong address - and the rest were backordered with no estimate of when they would be in-stock. They had no problem with charging my credit card for all the items despite having no idea when they would be getting the parts in.)

The names in (italic) refer to the names on the Bostitch parts list.

disassembling firing pin guide

undo the upper two bolts on the black faceplate (aka the trip cover) on the front of the gun (fig 1)
undo bolt at rear of nail cartridge (fig 2)
drop cartridge off of body
undo remaining two bolts on front of cartridge
pull everything apart and clean it
use appropriate grease on parts before reassembly

reassembling firing pin guide

thread the triangular firing pin backer plate (nose) onto stainless steel arm (upper trip) as shown (fig 3)
place the rectangular safety trip rod (lower arm assembly) under guide hook on nose (the hook can barely be seen in the upper left of fig 4)
put fork of the stainless steel upper trip around lower arm assembly, just above the thumbweel adjuster head (fig 4)
place the faceplate (trip cover) over nose and set aside for a moment
now place toothed plate (fixed core tip) onto nail cartridge (fig 5)
place the trip cover/nose assembly onto nail cartridge assembly
replace lower two bolts on nail cartridge on trip cover face. The shorter bolt goes on the lower right, when facing the trip cover. (fig 6)
place driver plate behind firing pin; note the orientation of the indentation on plate to see how it will align with indentation on nose (fig 7)
turn body upside down, drop spring into hole near firing pin (fig 8)
place the rear of the nail cartridge assembly onto body where the bolt connects the two
thread the stainless steel upper trip carefully into its slot behind the spring, and the firing pin into firing pin slot (fig 9)
replace upper two bolts on trip cover face
replace bolt at rear of nail cartridge assy (fig 2)

disassembling frame cap

remove 4 bolts around head (frame cap) (fig 10)
catch spring and rubbery head valve diaphragm

reassembling frame cap

look inside cap and find the narrow groove where the upper ridge of the diaphragm fits into; look at the top of the white plastic sleeve inside the body of the gun and note the bottom groove. The trick will be to get the diaphragm correctly placed between the two when placing the cap on the gun.
first place spring and head valve diaphram back into frame cap, making SURE that the ridge on diaphragm (fig 11) fits correctly into groove in cap
GENTLY place cap onto body, twisting slightly to make sure that lower ridge on diaphragm fits correctly onto groove on white plastic sleeve
If the diaphragm is not correctly placed (or if the gun is operated at too high of a pressure), the ridge of the diaphragm will blow out of the grooves in the cap or the sleeve, and allow air to escape around the trigger area instead of firing the pin. Note the two blowouts in this diaphragm. (fig 12) Even when the diaphragm is apparently creased by blowouts such as these, it can still be fit back into the groove and will eventually retain its shape.
replace head bolts (fig 10)

replacing piston driver / firing pin

disassemble frame cap (see above)
pull plastic sleeve free of body (fig 13)
pull piston driver / firing pin assembly out of plastic sleeve
replace with new piston driver / pin assembly
orienting the firing pin with its ridge towards front of gun [ridge can barely be seen in (fig 13)], thread firing pin through slot in body and press the sleeve/pin assembly back into place
reassemble frame cap (see above)