On the topic of belt conversions for mini-mills, some would say that there are only two kinds of gear drive. Those that have and those that will. Fail, that is. Mine lasted a couple of years and then the plastic gears exploded.
You can (I think) order metal gears, but let's look at a couple of factors. When the plastic gears fail, they may be saving some other part of the mill from breaking. Belt drive will merely slip under extreme loads with no damage to any parts. My belts hasn't slipped in use yet.
Another benefit of changing from gears to belt is that it's much quieter. With gears, I had to wear hearing protection for all but the slowest cuts. After changing to belt drive, the mill is really quiet at all speeds.
I'd advise going to belt at your earliest convenience.