I had this posted on fusionowners.org but keep seeing the question here. So here it is. Hopefully it helps a few people.
I was previously mislead on how the RAPS functioned and would bleed off. I ran into this problem and got some time in with it on Wednesday night. It seems pretty straightforward. I am going to steal D2kid's picture and rehost it here (thanks D2kid!)
Symptoms are a leak (generally a HIGH pressure leak) where the on/off RAPS meets the rail (rail = small black RAPS mounting plate)
First disconnect any air source (your tank).
Then cycle the gun to make sure no air remains in the regulators. (Its probably gone due to the leak already, but just be sure).
I personally disconnected the macro line (Black Air Hose)
Remove the RAPS from the rail by unscrewing the set screw on the side of the rail.
Rail Set Screw:
For the Flip RAPS (as thats the only one I have to verify) use a 5/64 allen key and remove the small flip lever bolt. This will allow you to remove the guts of the on/off (RAPS).
Flip Lever Bolt:
Remove the bolt.
*Notice that only one side of the RAPS has receiving threads. So the head of the bolt must go in this same side you removed it from when reassembling*
You now can remove the guts of the RAPS:
Guts ("Plunger" and spring):
I personally then took some rubbing alcohol and Q-Tips to clean the interior of the RAPS with a few passes of the wet Q-Tip and then a few passes with a dry Q-Tip. Watch the Q-Tip to make sure its doesn't start leaving cotton inside the RAPS. Set the RAPS aside to let it dry.
On the internal "plunger" and spring I cleaned all the old lubrication off as best as possible. I was unable to safely remove the O-rings from the plunger for fear of stretching them to much, OR ruining them all together.. I therefore settled by cleaning them while on the plunger and letting them dry.
I recommend DOW 55 for this particular portion of the Fusion. Its swelling properties should help you avoid future problems. At a bare minimum I would say use Dow 33 (paste) over any Tri-Flow or similar "oil" lubricants on these two O-rings.
Then reinsert the plunger with spring back into the RAPS. The plunger's pointed (small) end in first. Grab the lever and align it with the bolt holes on the RAPS and reinsert the allen bolt.
*Again remembering that only one side of the RAPS has threads for the allen bolt. The threaded side of the RAPS should NOT be the side you insert the bolt into first. As the bolt's end is only partially threaded it needs to go into the unthreaded side of the RAPS first. Tighten the bolt snug (these are small threads and a small bolt, don't be to aggressive here)
Once the allen headed bolt is secured for the lever. Attach the RAPS to the gun.
Please make sure the stainless ball (inside the rail) is dropped down (set screw on side of rail *NOT tight* at this point). To do this the marker is held right side up (as if playing with it) to assure the stainless ball has fallen down and is doing its job. Then position the RAPS your desired way (forward or back on the rail). I prefer the RAIL and RAPS to line up aesthetically (as pictured above).
Tighten the rail set screw until its snug (no need to over tighten here either):
Rail Set Screw:
Flip the lever a few times to assure you put it together correctly.
Your all set, air up and see if that solved the problem.
I have also been told that if it didn't solve the problem you may (your risk) choose to cut the plunger's spring a small bit. As the spring may actually be putting too much pressure on the O-rings. If I
were to do that, I
would start by clipping one coil at a time and never cut more than 2-3 coils off total.
If you still get leaks the O-rings most likely need to be replaced OR you have some internal RAPS wear or possible foreign material/flaw. Contact DP.