i've had my sure m447 cartridges and tips for a year now...they've seen moderate use and one on them will only pickup audio singal from the left channel...this happens about 3 or 4 times per session...i fix it buy removing the headshell from the tonearm and removing the stylus and putting it back in.....my quesion is, is it the tips that are goning or do i need a new cartidge?