If they paid $18,000 for the machine the cost to repair will almost total it. The router head can be complicated as that is the tracking of the router and must have the precision digital tracking devices in it. If you have to rebuild the head you will also have to recalibrate the devices which can be expensive. I worked as an Ops manager for a company that produced capital equipment involving precision air bearing tables offering high precision X-Y coordinate positioning. Can easily take hours to calibrate the devices.
I guess you get what you pay for. The units selling for $90K are 6 - 7 years old so what does a unit selling for $18K have for a history to it.
Imagine putting Million orders at the mercy of *very old* equipment. Kinda like running a taxi service with a 75 Chevy on 300,000 miles.