Ok, having done all that, remove the injector pump and watch for any shims installed under the pump, take notes and pics if necessary, replace EXACTLY as removed.
The fuel delivery rack can be cleaned by soaking the pump in diesel fuel, scrubbing with a parts washer brush and very carefully tapping the delivery rack slider with a rawhide or brass hammer if needed to make it slide in it's slot.
If you undertake to dismantle the pump, do only what is necessary to free the rack up and make use of reference marks for alignment and tightening. This is critical when you do not have test/measure equipment for the pump.
Your job here should be to simply clean up the delivery rack and to ensure that the one moving part you see, can actually move it's full range of travel, effortlessly.
Kubota Injector Pump Rack.pdf