transmission shifting issues GPW

[Kendall]

Hi,
I have a friend who is asking for my advice about his GPW and transmission issues (he knew I have military jeeps, and there might be some similarities among the different models). In order for him to shift into reverse and/or 1st gear he has to lift up on the gear selector lever (it then shifts fine into 2nd and 3rd). Can the cover of the GPW's transmission be lifted off as in M38s? Could it be as simple as it missing a ball and spring (WO-635837 and WO-635838)?
Any suggestions would be greatly appreciated.
Thanks,
Kendall