300E 103 motor - Stuck plug wires...

[Hit Man X]

I was going to change the plugs on my chum's '87 300E today and all the plug wires minus one, were stuck to the old plugs. They've been on there since '87 as they had the OE part number still stamped on the one that came off!

Anyway, is destruction of the old wires the only way to remove them from the old plugs? Would trying to soak them in PB work to loosen them up enough to remove?

I just do not want to get caught with my pants down by having broken wires and the end stuck to the plug and not being able to get my plug socket on there...

Thanks