I removed the offending slot, cut 120mm dia hole in the back of the machine, mounted 120mm powerful 12V computer fan on 6mm plywood to correspond with the hole, printed 120mm square to 100mm round hose connector, blocked all holes around the machine and propped the lid 8mm on two plastic feet. This creates nice airflow across the cutting surface.
@Nedman How is the k40 working with the exhaust fully removed? Did you just remove the four bolts in the back and front to remove that?
@Abe_Fouhy it works just fine without the internal exhaust vent. If you read the post above I had to removed the gantry (four bolts) and unmount the tube because of clearance issues with one of the tube mounting bracket bolts. K40 cases can vary so you might not have to unmount the tube on yours. If you remove the gantry I recommend using a marker to create registration marks on the gantry supports to make lining it back up easier.
@Nedman Thanks so much Ned, I did reread that, sorry for the double question. I appreciate the help.