Trimming silicone heaters

I have a silicone heater that just barely doesn't fit on my bed.

I want to trim about 2mm off one of the edges so it's not hanging off the edge.

On the other hand I could cut a couple 3mm half-circles out of the other side, to clear some screws, then I could shift the whole thing over a couple mm.

I'm not sure if either cutting a couple mm off the edge, or cutting a couple tiny notches off the side will definitely kill the heater or not. I know there must be some kind of conductors that run inside the silicone heater, but what are they? And do they run right next to the edge? And is the whole heater in electrical series, so if I cut 1 wire, the who heater is dead?

Can you countersink the screw heads instead?

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I used standard scissors to cut a mm or so off one of the edges, and I cut little notches out of the other side to clear the screws (they aren't just screw heads; they stick out). So far so good. I have to assume the heater wires are set back from the edge at least a couple mm. There is an xray photo on this forum somewhere that shows the wires inside the silicone and none of them went closer than about 5mm from the edge.