Rockola 488

Hi
I have a selection problem with this machine.The machine selects ok for selections ending in 0,1,2,3,4.
For selections ending in 5 the its a bit hit and miss sometimes the selection will be ok other times it will select the next record on(for example- if i select 155 it will select 165)., note the digital display is displaying 155
If i make any higher selections for those ending in 6 and 7, it will not select the right record and will be 1 or 2 record spaces further on(for example if i select 157, it will stop and select 177), note the digital display is displaying 157.
Has anyone any suggestions or ideas, it may possibly be a logic board problem
It seems if the machine counting process is out of syn
regards
Seancalla