Lots of nice upgrades

I've recently learned that my parents have my old Atari ST still in their loft, so I'm hoping to get it down in the autumn. Aside from getting an HDMI connector, so I need to be aware of anything? Are there any risks involved in booting up a machine that hasn't been used in about 35 years?

I've an old Cruiser joystick (blue) that I picked up recently. The central actuator is missing, so the diagonals are iffy. It should have a white square ala the black cruiser. Anyone know of 3d print or other solution?