I replaced the TM controls on our boat this year for that very reason. It just seems disconcerting that you'd have to jury rig your throttle with a bungee cord. I think a lot of people resort to this instead of replacing worn throttles as most are intended to stay in the set position. The TM controls have a series of friction plates to hold the position and eventually they wear out beyond the ability to adjust them.
I've seen too many return springs on carbs that have enough pull to return the throttle to idle. Why that happens is usually a problem with returning to idle due to worn or corroded cables
or too many bends in the cable enroute from controls to engine
causing more resistance.
Pro for bungee cord controls: Cheap
, good indicator for next owner on level of maintenance
, or lack thereof, the boat has received.
Con for bungee cord controls: Cheap
, could it be a hazard in an emergency
? Dunno, maybe.