Sony TC-78 cassette deck doesn't start play

hello to all of you ... I'm talking about the sony stereo cassette dek tc-78 vintage.  In play it does not start and I miss in rev and fwd although I do the exchange automatically but you can hear the motor spinning!  I opened it and saw that the 2 straps are still intact despite its age. Am I obliged to change them?  the problem is another?
 thanks Lorenzo.