Meisner 22 winch service

[sheepstations]

Hi, I want to service my Meisner 22 winches but am a bit stumped how to pull it apart. There is no obvious central bolt with an Allan key head that can be undone to remove the main winch drum.

Where you might use an Allan key or screwdriver to remove the central bolt, there's nothing there to unscrew.
I have scoured the interent and the closest thing I can find is a reference to "Use the Holmatro top-cap key to remove the top cap for inspection and servicing your winch."
So perhaps there is a custom tool required to do the job? Unfortunately the web link to Holmatro is no longer working.
So any input or suggestions would be appreciated.
Cheers.
JR