Something is wrong. If you loosen the locknut, the slotted shaft should turn easily CCW. Do not tighten it Clockwise, that may ruin the Alda! You should always write down (or remember ) how far it is rotated off "normal" - one to two turns CCW should be more than enough to make the engine run substantially stronger than factory setting, and it will also start blowing smoke more than normal too!
Dieseldiehard
1971 220 (gas) 4-spd manual 104041
1979 300TD w/ ’85 turbo engine 289560
1983 300D 237490
1985 300TD 206150