The Neu motors have a much thicker front plate, something like 4-5mm. The Feigao motors do too. It seems like the Medusa motors are 3mm, or less, judging by the nature of the problem. My Lehner XLs also have a thin front plate, but they are smaller, lighter motors.
Those are 36mm motors, right? You can try
these mounts. You would want the "05" size.