<"Actually, the shaft may just need to be cleaned. Some lubricants will 'catch' dust and make things worse.">
Agree.
I had the same problem. I was cleaning the helm and dripped some Malco UV protectant on the shaft by mistake. I just wiped it off and went about my business. When I closed the vent, the motor ran like brand new. A bit of WD40 on a paper towel to wipe the vent and engine hatch lifts is now routine maintenance.
HTH