[39portlander]

This would be a great question for Mac van Pelt, looking through the "In's and Out's" I did not see a length given for the detent springs, possibly you have a side cover spring #7234. I never recorded the spring lengths when I refurbished my 39 toploader.

As far as keeping thing in gear that usually is a worn thrust washer, also wear @ the thrust washer locations in the case should be checked.

Let us know how you make out. The spring from Fleabay could be for anything, do yourself a favor and talk to the expert, vanpelts.com for the correct part.