There are no gaskets in the older actuators, other than the one that keeps the connector block , Reed switch and ferrite wheel dry, plus the two above and below the commutator. Take out the two long screws and remove everything with some gentle persuasion, you can make up new gaskets with a template and paper from any decent motorcycle and outlet dealing with pre 80s bikes.
Seals will be what you have photographed, the gearbox clamp arrangement and the cable clamp, all of which should be replaced.
Then find a suitable bit of pond membrane cut so the liquids can remain in them whilst the actuator is sitting in ‘wake’ (cheap offcuts from any carp outlet) and leave for as long as necessary.
I used a dustbin which also contains the engine parts from vintage bikes so I don’t need to economise on the liquid. Turning over regularly as the actuator ends stick out the lid.