The tranny on my 940 turbo has been shifting a little sluggishly lately. On a long trip a couple days ago it shifted out of OD and wouldn't shift back up. I stopped and manually cycled the kick-down cable, and the tranny shifted into OD when it was supposed to the rest of the trip. When I pulled and released the cable it didn't initially return to a taught position, but after a few cycles it did. Is there a spring in the transmission that returns the cable to the idle position? Could that spring be weakening? Can it be replaced or do I need to replace the whole cable? One other thing I noticed was that the little rubber cap closing the sheathed length of the cable at its throttle block termination had been cut thru by the cable and left a sticky residue on the cable. Could this have contributed to the transmission's slow shifts?