Chain Stays On Small Sprocket

[pomondn]

I just purchased an older 12 speed Schwinn 'Super Sport' from a friend who had it stored as a second bike but has not used in quite some time. It's been awhile since I last rode a bike and left the gear setting where it was when I bought it. Today I took it out and started shifting to get the feel. Now I have a problem. When I try to use the right shift lever to move chain from smallest back sprocket to a larger one for climbing hills, the lever doesn't stay in place but moves back down thus moving the chain back to the smallest sprocket. I have to manually hold the lever up in order to have chain stay on larger sprocket. Any ideas? Thanks!

[Alex Ramon]

It sounds like a problem with your shifter, like the pawls aren't catching inside. Do you have the rapid-fire style with thumb and forefinger levers? If so, you might be able to squirt some oil inside to work out any gunk that may be causing the springs to freeze up. Otherwise you may have to carefully take it apart to see what condition the guts are in. I'll be making a tutorial that covers how to do that...