On the subject of K4s and undercarriage problems, there was a big incident at Filton during their conversions when one main leg kept getting stuck and wouldn’t lower.
As I understand it, after several unsuccessful rectification attempts, the crew refused to fly it until it was fixed. A decision was made to see what was causing it to stick and the main Actuator was disconnected. Unfortunately, when the U/C was operated, it failed to stick and it came down under its own weight and nearly knocked itself of the jacks. It caused considerable damage to the wing.
I don’t know if they ever found out the cause of the original problem.