Sliding Door Intermittently Fails to Engage when Closing

I have a 2006 Dodge Grand Caravan with a sliding door issue. The driver side sliding door will open using the typical means, but when closing it fails about 25% of the time.

When a failure occurs it sounds as if a motor is starting but grinding when it attempts to engage. The noise compares to a clutch attempting to engage and failing to. I attempted the following repairs:

1. Replace door lock actuator

2. Replace sliding door motor

3. Replace sliding door motor cable

4. Replace sliding door “chain cable” in the track

5. Grease tracks

I’m at my wit’s end with this one. Is there anything else you may suggest?