[rlowe61]

Based on description and the proto-typing conducted at the beginning of the season, I would have to say too much compression.
First you'll get a hook from a slanted disk trajectory, and possibly a spring type action as the disk decompresses against the wall.
Though we are way too deep into the season to change anything drastically, if the disk is lifting due to compression, it's too much.
624, worked on many variables to include, but not limited to; wheel diameter and material type, compression between wall and wheels, radial vs linear shooter, type of oppossing wall material (aluminum, wood, different type plastics, foam), length of follow-on wall (after it leaves the wheels).

Good Luck. Maybe a quick fix would be the ablity to adjust the motor distance from the wall