I understand your experience but, anyway, if it were an hardware problem, that would also manifest when using other software. Has I previously said, the problem is only there in DJay. When using Virtual DJ there’s no problem at all…
I recommend that you take a look at the following thread where Algoriddim recognizes the problem and states that is a bug correction coming in version 5.2:
https://community.algoriddim.com/t/play-pause-stops-working-and-sticky-scratch/26833
