Failed roller bearings will result in stiff and jerky flash cover motion often accompanied by a scraping sound. The scraping sound usually becomes worse as the flash cover is closed.

If the lock cylinder(s) fail in the extended position, flash cover movement will be very difficult if not impossible. When a single cylinder fails, the flash cover will skew and bind. If both lock cylinders are stuck in the extended position, look at the condition of the pnuematic system.

The lock cylinder rods are supported by linear bearings. Failure of the linear bearings or damage to the rod will affect flash cover operation.

The lock cylinder control valve is a 4-way pneumatic valve. Failure in the lock position will extend the lock plungers making flash cover motion very difficult or impossible.

Failure in the neutral position allows flash cover motion with detent positions but securely locking the flash cover is impossible. Minimal effort is required to move the flash cover even when it is actively locked by the solenoid valve.

Failure in the unlock position allows unrestricted motion of the flash cover. No detents are present.

Detents are provided by a spring loaded nylon tipped plunger and a low friction strip with pockets at the detent positions. A badly gouged detent bar or damaged plunger tip can cause problems with flash cover operation.

• See Servicing the Flash Cover Detent Components

A cable cable system installed in the flash cover ensures linear movement and prevents skewing regardless of where the operator is positioned. Worn or damaged bearings in this system can cause skewing or binding. Stretched or broken cables or tensions will also exhibit the same symptoms.