When I bought the Kubota M59 HST it had 1100hrs and a couple of rough previous owners. The range lever was bent and didn’t align with the shift marks and hard to change ranges. Straightened lever and over time with clutch, brake, gentle pressure over enough time it become easier and quicker to change ranges. Frequently have to shift between medium and high. Love the “plus” high/low shifter for each range.
The Kubota B26 bought used with only 50hrs had similar experience. It has no foot clutch. Hold the brake to shift ranges. Believe the manual says it can take up to a minute. It too has gotten easier to shift with use. Agree with Mikester that sometimes use the HST pedal to relieve drivetrain tension to improve range shifting. Gentle pressure and patience helps.