I have a 94 325is that appears to have had an aftermarket shift knob at some point...the shifter has scratches and marks from some type of allen key shift knob. The knob on it now is oem, I believe from a newer 5 series, it has the fake wood and 6 speed patern. I like the way it looks but it pops off. Is there supposed to be a clip that I may be missing? Maybe if I change the shifter it will cure the problem...does an M shifter (not knob) fit and is it any better? Thanks!