Turntable arm slides across record, Am. D.J.-1500

See what type of cartridge is installed in the arm. Manufacturers use common cartridges in turntables, such as Stanton, Shure etc. Detach the head shell from the arm (it usually slips right off via a locking ring and four-pin mini plug) Look for the manufacturer and model number on the cartridge. No need to remove it from the head shell. On most modern cartridges, the stylus (as they are called, rather than the needle) simply slips off and on. No need to remove the entire cartridge (via screws) and re-align it. In fact, many DJs bring a set spare cartridges and styli on a gig, already mounted in head shells, and simply interchange them as needed. When you have the make and model of the cartridge, go to Radio Shack or use their website to order a new one...or  two. Or go to Google and enter "phono stylus" as your search term. You will find reasonably priced styli for nearly every cartridge imaginable. I operate 50 year-old turntables and am able to find replacement cartridges and styli on line. Ebay also has a number of listings, by make and model of the cartridge. When the new stylus arrives, observe how easily the old one comes out of the cartridge- usually pull and slide - and slide the new one in. Re-insert the head shell on the arm, tighten the locking ring, and you're good to spin!