Replacement Knobs for TR6

[John Mitchell <jmitch@snet.net>]

Hi everybody,  Has anyone had problems keeping the replacement knob sets 
for the late model TR6 from sliding off?   Even though they snap onto 
the shaft, they seem too loose and slide easily back off when I use the 
control.  Any suggestions for keeping them on?    Thanks    John 
Mitchell   76 TR6