Congratulations on your Rocketeer, cabinet, and goodies. Use two hands to open the door over and to the side of the needle bar as it breaks easily and is difficult to repair. The hinges are not strong enough. Brace it with your hands and open very carefully. Be gentle. It's rare -- at least in this area -- to find a machine in the shape yours is, and with the needle bar door still intact, too.
I was given a Singer 500 (in a cabinet, with attachments) which is cosmetically as nice as yours. It took more than 15 hours to get that machine cleaned, oiled, lubed, and into proper sewing condition, as it had not been used in many years. Someone had fooled with lots of screws and settings, also. People on this board had very helpful suggestions for what how to adjust it at various points. (Thank you all so much!) It sews beautifully now and I use it often.
Cricket