Replacing RSX 7 Speed Shifters

I have a 98 Cannondale R300 Road Bike with RSX group and the left shifter does not work on it. I have tried flushing it with tri flow and it did not work. I want to replace them with something better but was told it would end up being a huge project.

From what I know:
The bike frame stays in the back are only wide enough for a 7 speed cassette so I am quite limited on options if any for replacements.

I have looked for direct replacements but cannot find any. Is it possible to use other, newer and or better shifters with my current 3x7 gear setup?


I just started 3 weeks ago and have really got into but need a decent chunk of time to save up for the new bike so overhauling this bike is not my idea but I would like to change a couple things.

Thanks in advance.