The "TMP gearbox workshop manual top" refers to the technical procedures required to service the upper drive shaft housing. If you are attempting a DIY repair, the most critical resource you need is the and the Shim Selection Chart specific to the model year of your Toyota Marine drive.
: Check via the dipstick integrated into the filler plug on top of the gearbox. Be precise, as the volume between "fill" and "full" is very small. 동이공업 Service & Repair Guidance