Gear selector detent How to check

Any one got some info on how to check the problem ? I have lost the spring resistance between neutral and moving left to engage reverse .I can’t find anything useful in the books
Thanks Jim

Did you try squirting some oil on the coil spring and the shaft that moves left and right? The shaft is stuck.

That could be a likely cause , There is some slight resistance at the end of the travel .Thanks

Still not solved . I have soaked it and jiggled it but still stubborn . where is the ball bearing ?

The single “ball bearing” is inside the “housing” of the, I’ll call it the “Reverse Lock-out”…
Take ALL that mechanism apart, clean the hell out of it, THEN, using some 600 grit (or finer),
sand the “rod” to shiny smooth… might even roll the 600 into a cylinder, with the grit “Out”, then polish the inside where the plunger “lives”, as well… In fact, clean ALL the shift linkage parts and pieces to a high degree worthy of an XK Jaguar!. Oil liberally then reassemble…
The “detent” WILL give you “resistance” when going into reverse (I “pop” my gear lever into reverse… all the rest “slide” into each gear detent smoothly).
My G-Box sat on two 2x4’s, bellhousing down, for twenty+ years. The “grease” on the shifting mechanism was all but solidified… When I rebuilt the g-box (a year or three ago) I made it a point to disassemble and clean the gear lever “assembly” (new bushings, etc.) While I have NOT driven my 120, yet, static it shifts very smoothly!
Charles Ch #677556


The ball #44 is under the shaft and there is a spring #45 under the ball to push it up into the notch in the #41 shaft. The hex head screw and locking nut adjust the tension on the spring.
If a squirt of oil hasn’t worked, then the spring is full of gunk and you need to take the #40 reverse selector off, take it apart and clean inside it. There is a square head screw with locking wire underneath that you need to remove first, then the reverse selector will slide off to the rear.

Thanks for all your help . I partially dismantled it and seems ok .

And just HOPE that square head taper bolt doesn’t shear…! Maybe a slightly stronger spring would also help?

The green arrow is the spring tension adjuster screw and lock nut. Turn it upwards if you want more spring force on the detent ball, but don’t go too far or the ball will have no room to move and it will not shift into reverse.
The red arrow is the screw to remove the entire selector if you want to clean it out, which is usually all they need.
green arrow spring adjuster and red arrow to remove selector

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I meant that maybe the horizontal spring could be a touch stronger? They probably relax a bit with age anyway.