These spots can be minimised and even eliminated by not "fanging " the saw back into the cut. This is counter intuitive to normal CS where the revs are maxed before being applied to the wood. Take the revs up to 2/3 to 3/4 WOT and then apply the mill gently and steadily to the cut and then build up to WOT over a couple of seconds. If marks are still evident, this is pointing to lack of rigidity in the mill frame, a common symptom in well used mills.
Judging by the temp gauge on my mill 15 to 20 seconds of idling makes relatively little difference to cooling. When the saw is stopped from WOT the temp shoots upward dramatically showing that a large amount of residual internal heat is present and this takes many minute to come down to idling temperatures. Idling for 15 - 20 seconds and then stopping does not reduce that temp spike that much and I found that I had to let idle for about 2 minutes to get the temp down to near idling temperatures.
I have one and tried using it and found that because the saw is such a small and variable temp target there is no large enough area on the outside of a saw that really gives an indicative temperature of what it's going on inside the saw. The best things are exhaust gas analysers such as are used on RC vehicles.
