Weird Motor Problem

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I recently fully upgraded my Tokyo Marui SIG 552 internals with the following parts:

King Arms 7mm Gearbox
King Arms 7mm Oiless Metal Bushings
Prometheus Stainless Steel Shims
Prometheus EG Hard Double Torque Gear Set
Systema Gearbox Spring Set
Systema Stainless Steel Stopper Rail
Systema Tappet Plate
Prometheus Air Seal Nozzle
Prometheus Aero Cylinder Head
Prometheus Stainless Hard Cylinder (A Type)
Prometheus POM Piston Head with Bearing NEO
Prometheus Hard Piston
Prometheus Non-Linear Spring MS135SP
Prometheus EG Smoother Spring Guide with Bearing
Prometheus 6.03 EG Inner Barrel (455mm)
Firefly Hop-Up Rubber Sleeve (Hard Type)
Big-Out Hop-Up H-Hop (Black)
Unconventional Airsoft Trigger Master MKIII MOSFET Unit
Prometheus EG Element Cord NEO Wiring
Prometheus Gold Mini Battery Connectors
King Arms Gold Motor Connectors
Systema Magnum Motor (Medium Type)
King Arms 11.1V 1100mAh 15C Li-Po Battery (105×20×17mm)

Ever since then my AEG has been working phenomenal and is still working phenomenal! But just yesterday, I took it apart so that I can tighten the screw that holds the charging handle on to the bolt. Because if you've had or own a Guarder Steel Bolt for the SIG 552, then you'll know that the screw that they supply with it isn't as long as the stock screw for the stock plastic bolt. So over time it gets loose, but I only took apart what I need to, to be able to tighten that screw. Anyways, when I was taking the Systema Magnum motor out of the pistol grip, I noticed that the whole inside of my pistol grip, around the motor, around the motor connectors and wires, and on the motor butt plate, that there was some kind of dust build up. I'm not really sure what it is, but it's really fine like dust and is dark copper almost redish in color. What could be causing this build up inside my pistol grip?

[Amos]

Your motor height isn't set properly and that's probobly metal shavings from your pinion gear

Ps. If you can afford all these parts.. You can pay Tirador for them