Detent Springs??? More info please?
Clicky:
http://www.marlincrawler.com/hardware-tools/hardware/heavy-duty-shift-spring
EDIT: Sorry just read the opening post. The spring above is for a transfer case, but the same applies.
Popping out of first gear is most likely the sign of a worn out center bearing retainer plate. I don't believe the retainer is a serviceable item and therefore I think most rebuild shops just slap it on and reinstall it without shimming or replacing it with a heavier duty unit (like we would since we manufacture them). It could also be a worn shift hub or a wasted counter shaft bearing but you'd certainly have hoped those to have been properly inspected & serviced by a rebuilder. None of these can be fixed with external repairs such as our HD seat/socket and HD springs. They can help, but are more like a band-aid for a problem that will only get worse.
Have you checked for anything more obvious such as interference between the shifter and the boot, or the boot and the cab? How about a broken motor or transfer case mount that is allowing the drive train to rock so much that it pushes the shifter up against the boot or body thereby popping it out of gear? I've also seen a rusted rear drive line slip joint cause a transmission to pop out of gear by pushing or pulling the drivetrain forward or rearward based on power or coast conditions. I've also seen a broken shift handle spring, the spring that is concentric with the handle and preloads the handle ball into the transmission seat. Without this the handle could flop around and provide means for the transmission to come out of gear. How about a 3" or 4" body lift placing the bend of the handle at an unnatural position too close to the interior boot and/or body.
When you say you've replaced the seat and socket, were these just OEM pieces or our Heavy Duty ones? (
see here)
The first thing I'd do it remove your interior boot so all you see is the shift handle and its small shift handle base boot (keep the base boot on so ya won't have gear oil splashing all over the place). Then watch the handle closely to see what is causing it to pop out: Is the handle moving directly into the body? Does it no longer pop out with the interior boot removed? Is the transmission itself moving all over the place and causing the handle to jam up against the body?
Good luck!
BigMike
