Just to be sure, first check the cartridge on your arm to make sure it is in fact the original, and not some other cartridge due to an upgrade. (sometimes the manufacturers varied things along the way too)
If in doubt post a photo...
The cartridge/stylus the previous link pointed at is originally manufactured by Audio Technica - a range of styli are available:http://www.turntableneedles.com/search. ... &search=GO
The original AT ones are consistently high quality.
As you can see from this link you can start with a conical and upgrade to an eliptical...
You can often find bargains for this type of stylus on ebay, but not all are of high quality... so some caution is advised.
bye for now