Lower Rear gear door not closing completely

[ET57C]

On a recent flight in my 1979 P337H the gear took a long time to retract. Low fluid was the problem and has solved the issue. Since then I have noticed the lower rear gear doors do not fully close. There is a 1/4" gap on both outboard sides. Previously if the plane sat for a few weeks these same doors would sag down open but as soon as the master switched on they would close tight. That same thing happens now but they are not fully closed. I can push the doors closed easily, the 1/4". When I pump them open to inspect, they are rigid with no slop or give. My mechanic has adjusted the rods but that did not make a difference. The issue is not to an adjustment but seems to be hydraulic. Reading the service manual it describes every possible gear problem but this one. There is mention of solving some problems with bleeding the system. I would think when the gear pump reservoir was low, it was caveating, while trying to get gear up and possibly allowed air in. I could not find anything in the service manual about bleeding the system. Has anyone had this issue?