Slit section won't move, won't return, or is noisy — troubleshoot and repair
The gantry's slit mechanism sets the actual scan slice thickness. If the slit plates won't move, won't return to their reference position, or the drive is noisy, use this page to match the symptom you're seeing to its probable cause — checked in the order below — and apply the matching fix.
Safety
Hazard: Motorized slit plates inside the gantry rotating frame
Consequence: Pinch / entanglement injury if the slit drive motor is powered while hands are in the mechanism
Avoidance: Isolate gantry/rotation power before replacing the motor or worm wheel, or before adjusting worm/worm-wheel setscrews; never test-run the drive with covers open and hands near the plates
Hazard: Slit assembly sits in the X-ray beam path, behind the gantry base covers
Consequence: Exposure to stored high voltage or unexpected gantry rotation while covers are open
Avoidance: Follow the gantry cover-opening/closing procedure and confirm rotation is locked out before reaching into the optical system (slit/wedge) area
Full step-by-step for Slit section won't move, won't return, or is noisy — troubleshoot and repair
All 3 steps are documented in the FSELIB Activion16 (TSX-031A) service manual — re-authored, web-first, with the real figures from the source.
Open the full procedureRelated Gantry guides
Source: 2D201-112EN*D §1.2.5 (pp. 42-43) — Troubleshooting and repair of the slit section. Preview re-authored by FSELIB — the full procedure with figures and steps is in the paid service manual.