After routing, the 1/2 inch bit was frozen pretty good in the collet.
Actually had to use pliers to twist it loose. The collet had not
bottomed out, nor was excessively tight. Upon inspection, neither the
collet nor the bit were warped or damaged in any way to cause a freeze
(at least by eyeball exam).
Should one put a bit of white grease or machine oil on the bit during
insertion? I hesitate, since drips might stain the wood. I'm not even
sure this would help the situation.
Thanks for any info,