You can adjust on the engine. The throttle and gear selection cables can be disconnected on the engine. Normally held in place with stainless steel R clips.
With the throttle gear selection on the remote then put it in neutral. Go back to the engine and use the adjustable linkage on the 33c cables to extend or reduce so it fits snugly. Use the locking nut to tighten against the locating linkage end. Possibly 8mm or 10mm nut. Put on, spray a little white grease to lube, and fit the anti-rattle R locking pin to secure.
Run the engine on muffs to test.
If it continues to be an issue, then think about replacing the cables.