Does anyone have a recommended brush for cleaning the burn chamber exhaust of a Harman P68. This is a couple of feet that also is home to the ESP probe. A( 2 1/2" cylinder brush) was recommended to me but I haven't been able to locate one. I find the typical pellet brush poses a risk of damage to the probe. A brush a tad "softer" would seem to me to work better with less chance of snagging the probe.