That's good, glad I remembered that I had them.These photos are great, gives me an idea what I'll be looking at when I take the cover off which I'm about to do... I've attached a photo with the bolts out and ready to lift it off. Is there anything I should watch for as the shift mechanism disengages from the gears?
Is that an 8speed gearbox? If so, it looks like a spring is missing. The ball? Or tapered slider? may still be in the hole.
Either way, a small mechanic's magnet should find it - that's from repeated experience.
Keep the springs into place with grease down the hole.
Some pics from a 135 service manual.
It's 6 speeds forward and 2 reverse. You can see the shifters in the photo, one has spring and a c clamp and the h-l range has nothing. Is this normal? I don't see any parts that would have fallen inside but they may have fallen further into the box and submerged in the oil. I don't have the right socket on hand to take out the drain plug to look. Can you advise? ThanksThat's good, glad I remembered that I had them.
IIRC, try to put both levers in the neutral position before you lift the shift cover off.
I'm hoping you find the locking screw beneath the range lever has come loose. If that isn't the problem, it will be on the rear of the gearbox at the range gearset - loose lock screw, broken selector fork or split drive collar. If any of those is the cause, you'll need to split the tractor at the joint on the right side in your picture.
Any of these possibilities will be easy and cheap to fix.