Paper negative, 4x5

I bought a broken Graflex and broken Kodak 3A Junior for a total of $15 and put together something to make 4x5 paper negatives with. The lens off the Kodak is 170 mm 7.7 anastigmat. The shutter works, but after I cleaned it, no longer holds open when depressed on the B setting. Kind of a problem, but I just went back to covering the lens with a changing bag (film, not diapers).