Recently I bought a 1998 klein stage and the brifters where busted. this was my first road bike and was only 120 so I dont even know how I did, even though im impressed with the bike. okay so to me problems. lets start with the right shifter. when I go to shift up a gear it will shift up about three gears and will stay there if I hold in the **** lever, but will immediately drop back down when I release the lever. and for the right shifter, if I dont touch it for a while it will shift up a gear then wont be able to shift up again for a while, but has no problem down shifting. I still ride it 10-15 miles a day, but im bummed I cant figure out this shifter bull shizen. any advice, or anyone selling new shifters at a reasonable price please contact me.
'''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
These brifters are 12 years old and were Shimano's entry level even then so don't expect a lot.
Try drenching them in WD-40 as dnomel suggested by spraying it copiously into every opening you can find, let it drain and repeat a couple of times. Let it dry and then lube with a light oil such as Tri-Flow. If this doesn't correct the problem, look for replacements as these brifters are not servicable.
The Klein Stage and Stage Comp (same frame but with 105 components) were decent bikes but were actually rebadged Treks as Trek had bought Klein a couple of years earlier. My son-in-law has a '97 Stage Comp so I'm familiar with the bikes.
BTW, a weak spot on these frames was the mounting of the downtube shifter bosses. They are not welded but held in place with a very thin threaded bolt that goes through holes in the downtube and both bosses. The thread can strip if subject to much loading and the bosses will then fall off. I've worked out a fix if it happens to your frame as it did to my son-in-laws.