The needle-up clutch is easy to adjust. The only reason it might not be repairable is if the pin in the hand wheel shaft is broken off. We had one in the shop last week with the pin broken off, and The Boss was able to drill it out and put a new pin in. Private message me if you need help adjusting the needle-up clutch.
If it continues to sew after you let up on the foot control, you might need to replace the foot control. The foot control is available through Brewer Sewing Supply for $199. The part number is 0026417012. You might be able to find it for less somewhere else.