Shimanos brifters in the 90s going up in quality were RSX, RX100, 105 & Ultegra. If flushing the shifter mechanism with WD-40 doesnt fix it, he should look on ebay or craigslist. If it is a 7 or 8 sp system he will need Sora brifters (Sheldons alternate cable attachment to make 8 sp shifter work with 7 cogs).