If you remove the large drain plug on the transmission (faces to the rear) Watch out for the spring (not too strong, but can catch you). If the clutch pack has failed, you should find metal shards, and dark chunks of clutch friction material in the suction screen(behind the spring). This type of failure can be very expensive !

Pushing with the inching pedal partially engaged, and/or the wrong oil can cause this failure (The oil spec is J20A or J20C)

If the clutch has failed, an exchange transmission is the best option...The shaft updates will add $$$$