I don't know if anyone is still following this, but if so I have a somewhat related question. I have a MS 251 with the single bar stud and nut. I brought it out the other day, fired it up, and did some full trigger chain running over clean wood to confirm the chain was getting oil. It was not. When I went to take off the cover and bar I had to really turn hard on the nut. When it did loosen, it felt like a sort of double release of torque. Cleaned everything up very well, and reassembled. I then noticed the cover did not seat evenly, and there was a gap between the bar and the main housing.
Took it apart again, and determined that the shoulder of the mounting stud is sitting up proud of the surrounding surfaces. Wear marks on the bar paint indicate contact only on the stud. Seems it has somewhat backed out, maybe About 30/1000's. Is this stud installed with a removable lock tight, and can I double nut the top threads and try to turn it back in? Or does it have to be replaced at a dealer?
Thanks in advance to anyone who can answer.
David in MD