Get on ME crankcase & cylinder page for 1974 115/135. Look at parts #52, 83, 66, & 45. Remove bolt #52 & nut #83. Separate bell rank levers #66 from #45. A pin fits thru the shift rod under the carburetors. It is important to keep up with all of the bushings. When putting it back put the bellcrank levers back together over the shift lever pin and over the small end at #83. Tighten the nut (#83). Put #52 bolt back thru bellcrank levers into block. Be sure all bushings are in place. If you are going to clean the carbs, this will go a lot easier the first time with the carbs out of the way. Once you do it and see what is going on it is a snap! Harder to explain than to do.
Dan in TN