Outdoor Power Equipment and Small Engines - Snowthrower drive doesn't disengage

I’ve got a ~4 yo Husqvarna snowthrower, (1030 STE XP). Often, when I release the drive lever it will keep going for a bit (sometimes quite a bit). I think the sticking is going on underneath rather than in the handle. I took a look at the mechanism, but I don’t see anything missing, loose, or broken under there. Should I try lubing it and, if so, with what? I’m between that and getting a stronger return spring. I’m certainly open to ideas.
Thanks.

return spring could be stretched. or could be the control rod needs to be adjusted.

The spring could be stretched and I could try another. Somehow I don't think it is an adjustment. When the drive doesn't disengage (if I'm not trying to avert disaster) I'll watch the externanal parts of this linkage. The lever (for lack of a better term) in the rear of the housing will move about half way and stop. The spring and rod that extend up the the hand controls appear to be slack. If at this point something bumps the machine, the lever will move the rest of the way.

The spring could be stretched and I could try another. Somehow I don't think it is an adjustment. When the drive doesn't disengage (if I'm not trying to avert disaster) I'll watch the externanal parts of this linkage. The lever (for lack of a better term) in the rear of the housing will move about half way and stop. The spring and rod that extend up the the hand controls appear to be slack. If at this point something bumps the machine, the lever will move the rest of the way.
Ok. That being the case, it needs to be lubed. Pick up and hold the machine off the grouond by the handle bars. (I use a "come-along" attatched to a cable around the rafters in my garage). Remove the "belly" pan. Follow the" lever" and see where it pivots. Spray the pivot point(s) with a good penetrating oil (PB Blaster) and work the lever by hand (may have to disconnect the rod) until it moves freely & snoothly for the full range.