Having too light of a spring may have it's own issue. The PO of my TCS must have installed a much lighter spring for the ball. It made 5th gear selection much easier but it also made accidental hitting of reverse on the 3rd to 2nd downshift more likely unless you are extremely careful, it happened to me a couple of times.
I think Peter wrote that the detent spring is a non standard size. If so, there may be issues getting replacements of varying strengths.
Peter, I misplaced the bits you sent me and may end up buying another set from you. I'll send you a PM if I can't find the kit.