I am not a Komatsu expert but, I would like to help, I am assuming this is a conventional wheel loader with a transmission with front and rear drive axles.
I have seen the yoke on the input shaft of the axle strip and loose the drive, this should make a little noise when it is slipping. I guess the loader won't push when the front wheels get light or off the ground.
A broken pinion or axle shaft would be the next thing to look for. Start by removing the final drive covers on each wheel. This is the small cover in the center. Remove the center gear and axle shaft. If you don't see any damage, lift the front wheels off the ground and look in the center of the axle to see if the differential is turning. If everything is in good condition, nothing broken you could have the spider or side gears in the differential damaged. Any failure should leave some large pieces in the oil. To confirm how much damage you have, drain the oil from each final drive and the differential to see what is in the oil. Run a magnet in the oil to determine if it is iron or other metals.
One odd problem I found was the tire casing on one wheel separated and the tread was sliding on the tire. This was on a non locking axle so, the loader would not push, just spin the tire inside the tread.
Have some on watch from both sides to see if you have tire or wheel slipping. Tires with very low pressure can do this too. It is always noticed on loaders without locking axles.
Hi This is somewhat helpful but it for sure is not the tires slipping on the wheels and this model does not have final or planetaey wheel drives. I was also told the only to get at the inspection hatch is to drop the axle but iwill check and get back to you. thks.
Ok, thanks for the reply. If it does not have out-board final drives, it must have in-board final drives. This would have a very large differential housing instead of the pumpkin shaped axles like in trucks.
If they made both axles the same, it will have a cover on the front were the oscillating hitch would mount for a rear axle setup. If you have room, this would be a very good inspection hole.
If all else fails, remove the fill or level check plugs to see if one has a magnet. It should at least have magnets on the drain, if no were else. The drain plug would mean loosing the oil though. Remove plugs slowly, the housings hold a few pounds of pressure to prevent water entry.
If you find anything, take a picture and upload it here. Maybe I can help a little more but, it don't have any access to Komatsu manuals.
I will OPT-OUT anytime you feel others can help more.