When I press the trigger on my nailer, I just get an air leak all of a sudden. From what I read I'm guessing the trigger value needs to be replaced, but was wanting confirmation? Are there seals or something else I should also do at the same time? I was also wanting to verify this is the right part?: Trigger Valve Unit FA205BA1
Yes, I'd say the FA205BA1 Trigger Valve Assy is certainly the part to replace if you simply have air leaking/bypassing through the trigger.
Most likely it's one or more of the o-rings that's damaged on the valve stem, causing this. Of course, it's best to be sure by replacing all of the trigger components, which is why Bostitch sells it as a complete Trigger Valve Unit.
This is also what the Bostitch manual suggests, as you can see in the attached image.
If you get air bypassing out of the top exhaust area, that would be indicative of another problem, probably the head valve seal or exhaust seal on the cylinder. But, if air is leaking solely out of the trigger area then replacing the trigger valve should do it.
