That behavior generally means the unit is gummed up with old grease and dirt. The ideal solution is to disassemble the unit, clean it and re-assemble. This is tricky because everything must go back in exactly the right place and in the right relationship with each other. You may be able to get by with something less.
First, reset the unit all the way, by hand if necessary. On the side with the circuit disc, pick one of the wiper fingers and mark it with a Sharpie. Put a matching mark on the circuit board. Then you can remove the nut and pull the wiper unit off the shaft. Make sure the ratchet wheel does not turn while removing the nut.
Now take some 600 grit sandpaper and sand the rivets until clean and shiny. Don't sand off your alignment mark! Wipe the board down with isopropyl alcohol and then spread a VERY thin coat of Teflon Superlube over the rivets. Clean up the contacts on the bottom of the wipers with a flexstone or the same sandpaper. Don't bend the fingers while doing this.
Reassemble the unit, matching the marks you made earlier. Now, step the unit up a few notches and then reset it. It should spin back all the way to zero. If not, you have two choices. Disassemble it all the way and clean the main shaft or, the inadvisable way, tighten the clock spring one turn. That should be a last resort as you want those units to operate with as little spring tension as possible. Tightening it may make it hard for the unit to step up - you'd just have to see.