So, it's obviously better to replace the switch than to try to repair it, and I definitely would schedule a shut-down. I've already spoken with the store manager about this, and he agreed to a night-time shut-down if the replacement is necessary.
The next thing is to determine about how long the replacement would take, so I can price the job accurately. The 1200a switch is the upper one of two mounted in this 4000a switchgear section, which is about 7' tall and about 3' wide.
I will have to arrange for independent power for lighting, plus any power tools I might need, so it looks like my inverter installation will have its first practical workout. So, about how long should I expect it to take, and will I need any special tools?