[David G4EBT]

If you just intend to connect the + ends of the new caps to the three red wires, slide a small length of red heat-shrink sleeve over the red wires before you join the + ends of the caps to those wires, then when you've soldered the joints, slip the sleeving along over the joint and shrink it. Otherwise, if the + tags to which the three red wires go are close enough for you to remove the red wires and connect the new caps directly between those + tags to the ground tag, just slip some red sleeving over the + wires of the caps. You don't need to insulate the negative ends of the caps as they're at ground potential but if they're close to other live connections, then of course it makes sense to insulate them.

While you're waiting for the caps to arrive, it would help if you looked closely at the wiring arrangements to gain an understanding of how they relate to the circuit and whether it's feasible to connect the caps directly to the three + ve points and ground, or whther you need to re-use the exiting red wires.