I didn't know you had spare carts already, in fact nothing ever can happen to them (except a dried outlet sponge by storing without clip).New yellow cart arrived today. Cleaned spilled ink from the head and fitted cart. The first print was fine, and no ink has leaked. Yet. The problem seems intermittent.
I'll report back if I have any further problems, but don't hold your collected breaths, I don't print often, and, as I said, it seems intermittent.