Why the high / low shifter on a eaton/fuller won't shift right?

no VIN told
no country told
no year told
no kind of transmission told , manual or automatic
the only clue is 6th gear,
my 2008 jeep has a 6speed manual transmission
SEE?
let me guess it is a M./T box and has manual foot clutch
and the clutch slips.
seems your shop in town is not so good.

top cause of gears not selecting is the gear shifter linkage is all messed up. (damaged, worn, or adjusted wrong)
or the
main clutch is dragging (bad) or slipping worse.
any shop that knows M/t can diagnose it, but not yours.
the old 6sp mt box has side lever shift links up to 1995
then later the Eaton Fuller FS6406A 6 speed box?2004 up??>?? no year truck told, why must any helper beg fo the year.
with classical. top lever shift and big knob end
the bottom of the classical lever. has tip and this tip can be plastic to stop noise but wears out fast and the H pattern fails to work this is super common super easy cheap fix.
even a $10 fix.


Eaton fix easy, nothing ever was so easy this failure
see the stick?
remove it and see the tip is damaged.
bingo.will not pick gears in the H pattern, or is RAndom
BOX GOOD
CLUTCH GOOD
SHIFT TIP NOT GOOD. A DIRT CHEAP PART.

It is a eaton fuller and it sounds like something is between the linkage rods.

how many gears in this transmission remembering that Eaton make from 5 speeds up to 21 speeds in their range of transmissions
so if you have a 9 speed box and attempt to select 6 gear without using the range change you will be selecting probably first again
Don't assume that everybody knows what box you have so include all make , model year , equipment application in your posts as they are not linked

make sure to bleed water from air tanks

Pop the four bolts out of the shift lever lift it up and to the left you will see that the dogs on right do not line up use a screw driver or small bar pry dog so they all line up and place lever back in place and bolt this all works easier with some one else holding the weight of the lever. MAKE SURE PARKING BRAKE IS ON and push clutch in and release any drive line pressure before you begin

the small air valve at the box will be suspect as they tend to seize up and not move
check that the plastic air lines to the switch or box are still intact
check that the gear knob is operational
some knobs are where you move the lever sideways to change the ratio and others have a pull up knob under the lever handle
the flick switch sometimes develops problems in the rubber"O" rings

Check the linkage..Might have something loose or needs adjusting

Check and see if your Vacuum Lines are broken... That is probably the issue

Have you Checked your Vacuum Line ? This is the most common issue with the High / Low Problems,....

You have bent forks inside the transmission and most likely the synchronizers are needing replacing.

I hope this helps - please rate me - it helps a lot- - Thanks "F"