hi, with any audio cassette player replacing erase or play/rec heads isn't really a straight repair.Can be costly.
When you manage to obtain the play/record head you have to mount it as the old one came out,resolder all leads onto new head.After this you have to realign new head so that you get full sound output,this can be hit and miss if you do not have a realignment test tape(test tape plays back a pure test tone)with this tape inserted you adjust the grub screws until the loudest volume can be heard,sometimes on small hand cassette players,with the tape door closed this screw can be adjusted down through a small hole in the door close to the audio head.
This procedure can take time,hope i haven't put you off!!!Tom
Tom, June 2010
