The Free Company (named after a person, IIRC) made wonderful machines - I love the looks of it - early 60's, I'm thinking? Is there any date in the manual?
Getting it running again will probably be easy enough that you could do most or all of it by yourself, depending upon how good the wiring is - that's the only thing that requires some technical skill.
Inspect the wiring from one end to the other and inside the machine. If there are any places where the insulation is crumbling or sticky or torn, decide whether it's minor enough to repair with tape or if it warrants being completely rewired. If the wiring looks good, remove the needle and bobbin, raise the presser foot and turn it on. Make sure that the handwheel is engaged and not turned back for winding bobbins and that the bobbin winder is not touching the handwheel, then step on the gas. It may be very sluggish or it may not start at all. If the motor runs and the presser foot is driven up and down, you're probably good to go.
Turn it off, unplug it and start cleaning the insides and underneath - all the metal parts - not the wiring or any plastic or painted parts - with acetone on q-tips. You will get dried brown oil on the q-tips and shiny metal will emerge from underneath it. After it's clean, oil it thoroughly and run it for a minute.
There may be a little (tiny bit!) of smoke or a slight smell of smoke or rubber. If there is any more than that, stop and unplug it.
If it ran all right with just a little smell, let it sit for a couple of hours, then oil it again and run it as fast as it will go. You will be able to hear it speeding up as hidden bits of dried oil soften up and are rubbed away and replaced with fresh oil. Run the machine for five minutes at full speed.
If everything goes well with that, then you can put a needle in it, check by hand-cranking it to make sure that the needle isn't hitting the needle plate or bobbin case, then thread it up and try sewing something, following the manual.
If it's still sluggish, repeat the oiling and running for five minutes at full speed and letting it sit for a few hours until everything breaks free and the machine is running fast.
Working on these old machines is a lot of fun - you do get your hands dirty, but you might enjoy this kind of work - and in the case of fixing your grandma's machine, it's especially worth it.
Good luck and have fun!