As I see it, there arn’t many technical people out there. I started my buisness with almost no money and no eqipment, I bought my first mixer for $300 put $200 into repairs, My brother now uses this mixer at his resaraunt.
To answer your question is, there is no need to be alarmed, with older mixers this is common especially with lesser known brands. As one reader posted; your machine needs lube to keep it operating properly.
My solution, seeing that we didn’t use the h hub, I made a plug out of plastic and a rubber o-ring from my local hardware store. $cost .20 cents