D8l reverse shift problems

[NovaScotiaD8L]

Hi guys, I have just started restoring a D8l 53y1980. I hope to put her to work land clearing. Biggest problem today is the tractor will shift all forward gears no problem and will shift all reverse gears when cold ( about 10 mins) after this, trans will shift into reverse only when shifting to 3rd and back down to 1st gear reverse. All forward gears work as they should. Just started working on this tractor. I have pdf service manual. If you guys have link to a better one that would help. Thanks
Evan from Nova Scotia.

 

[NovaScotiaD8L]

I should include some back story.
Bought this machine out of an old coal mine about 3 months ago. I would say she has not worked a full day in about 10 years other than just to move around and keep lubed up. When testing before purchasing previous owner said shifting problem was new to him and thought it could be siezed or stiff linkage. I pushed with her for about an hour and didn't have any other issues. Tyranny was down about 5 gal of oil. I've since checked all fluids and topped everything up. The kids have smashed the gauges out of the cab and I am in the process of fixing them.