Disk keep spinning/seek for a long time?

CD player of Technics SU-CH900 hi-fi, seems to have intermittent problem. It works sometimes (if i'm lucky) but most of the time it doesnt read/work. It keep spinning/seek for a very long time then displays 'NO DISK'. I've tried cleaning the lens/pick-up numerous time using jet spray, alcohol & cotton buds but it juz seems doesnt work. Could there be an alignment problem, pls help, tq.