I think that the natural springiness of the side panels, coupled with the keyways on the interior panels (which I can feel through the vinyl, but cannot see) and the perpendicular studs on the arm rests' shafts, keep the arm rests in place.
The dealership is a small (three-person) operation, and unfortunately one of the three has been out due to a death in the family, so I suspect that the remaining two have their hands full. I placed a follow-up call yesterday afternoon, but it was about a half-hour after the 4 P.M. closing time, so I left a voice-mail message.
I will look at My Ventrac. Thank you for the suggestion.
With best regards,
John