Help needed to repair the Telequipment D54 Oscilloscope

[GranpasScopes]

Hello! I was hoping to get some direction about getting two scopes my grandpa had back in working condition:

1. Telequipment D54 Oscilloscope (like the one here )

2. Tektronix 2215

I would like to get started with the Telequipment D54. Here is what I see after I turn it on:

i. With both channels turned off, there's a green dot on the screen slightly offset to the bottonm of the center of the grid. I can move this around with the top left adjustment but I don't know which adjustment to make it move up or down
ii. When I turn on either channel, the clear dot turns into a hazy column around the center of the grid as if there's a lot of noise on the input, but nothing's connected. I connected a lead to either channel and touched the lead to the 'test' hole but nothing changed
iii. Each channel has a AC/DC/GND switch. Should putting this to GND force the scope to display a flat trace on the display at 0 offset?

How do I go about testing whether the Telequipment D54 is in working condition and what to fix if not?

I am reasonably comfortable with digital electronics and basic passive and active components.

If needed, I can upload pictures for ii