May Birthdays 
planish
I found a spring laying around, cut it to what I thought was a good length, and dropped in. The wire it was made with looks a bit thinner that those at Musician's Friend, so it's probably not as stiff. The bar stays put when I push it out of the way, but there is very little resistance when I need to swing it into action.
Okay, a cautionary tale here about using "any old spring" found in a drawer.
I noticed it was getting harder and harder to install the trem bar when I took it out of the case.
Close inspection of the threads revealed that the spring I used was (A) getting shorter, and (B) getting chewed up by the bottom of the trem bar, and the chewed-off parts were sorta' welding themselves into the thread on the trem bar.
It took an hour or so of picking at it with a dental probe and small screwdriver tip under a magnifier to clear the threads again. Fortunately, the threads were not too badly damaged, and it will now go in fairly smoothly. Next time I try that I would put some sort of plastic cap on top of the spring, so that the top end of the spring cannot work its way into the trem bar threads. Or I could bend the very end of the spring in towards the centre and down a bit.
In the meantime, I'm using an over-sized spring that goes over the trem bar, with a washer between the bottom of the spring and the bridge. Oh - and a short copper tube and another washer up by the elbow, so that the top of the spring doesn't simply slide around the elbow.
—I'm not a complete idiot. Some parts are missing.
