Reply to Worn out cart/needle? Alot of skipping

Hi guys,

so i bought a pair of used stanton st150s with their used original stanton 680v3 hp carts, and i'm getting a load of skipping from them and their used carts/styli. Owner claims to have got em in 2009, but used only a couple of months.

Basically i cant even cue up a track properly on the 1st beat. Using the paper trick at the gap near the tonearm improves it to a certain amount.

How do you tell whether the needle/cart is causing this? Or how do u know whether the cart or stylus is worn out? I'm not sure if they are the problem causing the skipping, or the table is faulty in general.

Would hate to spend money on new carts/styli for it to make no difference at all.

If its the needles, should i replace the N680 styli or just opt for brand new m44-7 carts?

Antiskate is 0, tonearm height tried from 3-5, and counterweight tried 2.5-5 w and w/o the +2 headshell weight.

Generally a mix dj, learning some turntablism.