I got it out by disassembling the boom, taking it from the boat and solid punching,
you need to put the support in the right place, otherwise you might brake something you don´t want to brake.
If you turn the boom upside down, the support of the boom should be at the hollow output shaft, the one to which the stainless shaft is connected (with a little key). Slide two solid metal bars side by side under the hollow shaft and support them, so there is no load on the boom or the gear box housing when punching.
I´ll put the exploded view of the gearbox in the files section under Leroy Somer Gearbox.
If you work with an shaft extractor it´s the same thing: you need to put the support/metal bar of the extractor to the hollow shaft.
Walter (Noa, SM2K 436)