While changing plugs and removing the cowling on my '64 johnson trolling motor, model j.h. 19a, B101311...I messed up the setting mechanism and now I can't get the motor to run right...having to pull the choke out half way to even troll. She won't run high speed either. Seems like the brass shaft the lean-rich knob attaches to has allowed the knob to slip and I have lost the proper reference. Hope this makes sense...difficult to diagnosis with out the proper manual.