The 110-90’s dual hydraulic pump (one for steering, one for the linkage) is notorious for mysterious failures. The manual includes color-coded flow diagrams and troubleshooting trees for issues like "lift arms won’t lower" or "jerky lift response."
The 110-90 usually came with two double-acting spool valves. If your remotes leak down, the manual tells you how to check the detent balls and spring pressures, plus how to lap the spool valves back to a factory seal. fiat 110 90 tractor workshop manual
If you own a Fiat 110 90 and are experiencing issues, do not touch the tractor until you have consulted the workshop manual for these common procedures: The 110-90’s dual hydraulic pump (one for steering,
Unlike YouTube videos that skip steps, the manual provides logical sequences. It tells you exactly how to remove the cab without warping the floorpan, or how to split the tractor between the engine and transmission safely. Safety precautions: Lockout/tagout
Fiat used proprietary tools for certain jobs (e.g., the clutch centering tool No. 4980659). The manual lists every special tool. While you may not own them, knowing their function allows you to fabricate or adapt standard tools to do the same job.
Owning the PDF is step one. Mastering its use is step two. Here is a workflow for any repair: