The connection between our coil wires and BNC terminals was pretty awful (soldered wires broke off ) so we removed the old heat shrink and re-soldered the wires.  We then chose more appropriately sized heat shrinks (small one around each of the two soldered wires, a medium-sized shrink around the wires together, a large one covering the BNC terminal and the wire) and used the solder iron and heat gun to shrink them.