Hey gjk735 ,
I had a friend who was having the same issue with their OBD port, we tried just taping it to the plastic parts but it only lasted a few weeks. Wedged a piece of notecard in there and it's pretty snug now.
How large is the gap between the adapter and the holster?
Thin gap which is why I tried electrical tape. Today I saw a double-sided adhesive foam tape which I may try. First I will try the notecard solution.
I can appreciate the MacGyver solutions that have been attempted by you and htghtg. I recommend speaking with our Tech Support team (more specifically STC - Specialized Tech Care) or T-Force via social media as a ticket will need to be filed and passed along to the Technicians and Engineers.