[Stick486]

hello N/A and welcome to the forums.....

what's the country of origin for the bit..
do other brands of bits behave accordingly..
your bit shank may be undersized or out of tolerence...
the collet may be damaged...
you may be setting the shank too deep or not deep enough into the collet..

 

[Stick486]

Take your collet off and check it under a magnifier for cracks. As Stick suggested measure your bit to make sure it is a 1/4" or 1/2" shank and that the colle is also 1/4" or 1/2". If the router could have come from Canada it might have metric collets but most likely either the collet is broken or the bit is the problem.

if the bit came from China the shank could be out of tolerance...