Crackling through left speakers only?

Recently picked up an old Marantz system - PM 350 amp, EQ 20 equalizer, SD 1030 cassette deck, ST 450 tuner, TT 221 turntable. Don't know the history but they seemed to have been in storage for a while. Problem is when I hooked it up I get clear sound out of the right speakers but cracking out of the lefts. Any ideas?
Unfortunately the cassette deck is dead. Have yet to investigate.
Looking at a marantz CD73 CD player to complete this 80s retro system.
Would appreciate any helpful hints on the crackling and any ideas where to start on the cassette deck.