How I fixed Z banding on my 12" i3v. AL Y bed and solid state heat bed relay/PID

[dunginhawk]

I do think metal (I prefer steel, which expands only half as much as aluminum) is a requirement for the Y, and for the whole frame. I have a steel i3 from Createc with the mechanical bang bang relay. I like the clicking, which tells me it's working. And the steel Y (with glass on top of MK2 pcb bed) is unaffected by the heat swings.

so im wiring up my solid state relay, and the common from the PS goes to the input - and the + from the PS goes to the +.
However, coming off of that are 2 black wires, that arent labeled + or - and the bed doesnt seem to care and colins instructions dont have a positive or negative marking...
so thats throwing me off a bit... any help?
Edit: so i just took the + from the same block as the + from the PS and marked it +. so that should be good.. and the same for the common.... so i think the above is resolved.

EDIT :2 = seeing the above may be wrong also... Thomas Sandelar has a good video on wiring these, but its AC... this is obviously a DC relay... still searching

now im not sure how to hook it up to the rumba board... there are no spots to connect those 2 wires that go from the board HB out , in to the relay.... thoughts?
thanks