Undersized hearth with no signs of distress is NOT AR.
The function of a hearth is to provide a physical barrier to standing too close to the fire, and to protect floor covering from radiated heat.
Is the hearth on the floor, or is it up a height? some fires have different requirements for these, and some can be fitted with NO hearth, if high enough. (although probably not that one)
Also. I cannot see the bottom section of the ash pan cover. It typically has two openings, left and right, and, as I said, some fires have a diagram showing the minimum free area. I was not specific enough - it shows WHERE the free area should be. This is because inset tray fires are typically sold without specific frets, and the customer can select from a range offered by the retailer, so the fire maker has no control over the design.
I suspect that you are going to go down the route of "finding" a reason to disconnect. Why not do the job properly - maintain and repair as necessary, and charge accordingly. We are not called "service engineers" for nothing.
It probably just needs a good clean, andcorrect placement of the coals - and you may impress the client
