Silverlight 85w scroll sawn old model

[caretakereg]

I have just brought this scroll saw but having trouble removing the blade, its the bottom that I can not work out how to remove.
I need to twist the blade from side cut to front as it has 2 options and will need to change blades in the future, anyone had one of these machines that can help.

 

[caretakereg]

In desperation I gave the scroll saw a good look and on the rear side I found a inspection plate, 3 screws later I found the bottom of the blade.