I'm new to this forum and posted a plead for any leads on an MB-15 manual and service manual--I swear they do not exist of planet Earth.
However, new issue--odd issue. My stylus force gauge was broken in transit, so a very nice well known audiophile dealer near me offered to set the arm up for me. When he saw it he was incredulous because the counterweight and its inner black sleeve just flew up and down the tonearm. No way to do incremental settings, no way to set using a stylus gauge and secure the weight. The weight has two identical holes: one through the entire weight, and one directly below it on the inside of the weight (this I believe should fit the groove on the black plastic weight insert. "Balanced at 1.25 grams the weight was almost off the back of the arm. My cartridge is 6.5 grams and the arm is supposed to be good up to 10 grams, at least.
Okay, quite a poser for a first real question. Advice, comments, reprimands, ingenious fixes? All are welcome and appreciated.