No the gear box does not have a clutch. I have had this problem also. Mine would do the whole wash and then when it was almost at the end of the triple shine it would just sit there until it trip out the drive motor ran too long alarm. I have found bad bearings or a bearing has worn a grove in the shaft on the drive wheel. I just replace all 4 rollers and eight bearings on one this week. I found Bob Hill on ebay and purchased Stainless steel bearings for less than $80 each and they looked and felt like good quality bearings. I get my tractor with the front loader and lay 4x4 across the bucket and lift it up. make sure you have the switch off or it will try to move when you lift it off the prox.
