Question for the welding pros

[Cash3481]

I went to my parents house this weekend for their neighbors funeral. My dad asked if I would use his old stick welder if he gave it to me and of course I said yes.
I already have a new Hobart 190 for mig but thought this would add to my capability.
it's an old miller thunderbolt 225.
My question is this...
1. What maintenance do I need to do to it before I use it? It has set for several years (7-10). I thought I could use it on heavy frame welding.
2. Is it even safe to try and use it? I know it works (or should) he just hasn't needed it.
I'm new to welding but always looking to learn.
3. About what year is this model and can I find the user manual? I'll google for the manual!
I appreciate anyone thoughts or criticism on it's use.