What does the scope view look like for the bad side?

When your friend used your SL1, did he use his equipment (turntables/CDJs) or yours? If he used his equipment and everything worked fine, then it has to be something with your CDJ. And since it's CDJs, there's no needle/tonearm stuff to worry about, so really, that only leaves the RCA cable coming from the CDJ to the SL1? Have you tried a different pair?

Adding to what Konix posted above (thanks Konix), does swapping your left and right CD decks result in the problem swapping sides? In other words, does the problem follow the CD player?

i have an almost circular scope which then comes looking like the image. i have tried swapping the wire cdj and using it on different lines same result always. i tried the same cable on another cdj and works fine.

it actually shows up better at a lower threshold than the other.

Do you have the CDJ 'Master Tempo' key lock feature on or off?

Are you using the original control discs or burnt copies?

im using original control discs and cdj is not on master lock, image attached is the cdjs i have ndx200

Have you tried a different RCA cable or USB cable? Do you get similar results?

Are you using a USB hub or splitter to connect the SL1 to your computer or are you connecting it directly to your Mac?

What kind of Mac are you using?

i will try that tomorrow and let you know.

OK, thanks :)

SORRY FOR LATE REPLY SO I TRIED A DIFFERENT BOX, TRIED DIFFERENT CABLES SAME OUTCOME

It sounds like the problem is with your CD decks. To clarify things a bit, when you're using different CD decks with your box and computer, everything works OK. correct?