I had to change the fan belt on my BX25D. The too, required disconnecting the very same drive shaft. Hardest part was getting the belt around the radiator fan. I cannot fathom the cooling fan is more than a two hour job for a person who has never done it before and probably an hour job for a person who has done a few. I've not broken mine yet and I also have had and keep on a BXExpanded plate, I had the plate prior to the delivery of the tractor.
An expanded metal screen would eliminate most broken fans.
Perhaps rubber blades that flex or steel that would shred most sticks. Imagine a two piece fan that only needed bolts removed to take off a left and right half. Anyone tried cutting a stock fan in two? Can you cut off a broken fan and put on a two part one?
My Sears Craftsman has a similar fan, but belt driven and a single bolt. I trashed it the first year I had garden tractor. I bought five replacements assuming this would be common. Now 19 years later, I still have four spares.
Funny story. One day, I was riding around on the garden tractor, mulching leaves. Some sticks on the ground. I was thinking, what if one of those goes up and screws up the trans. Right then and there., the tractor stop going forward. Crap. Slogged back tot eh garage. Got a wheel barrow, put the jack in it, some plywood to lay on, tools. I jack it up, pul off a rear wheel, only to find a twig stuffed into the mechanism that permits freewheeling (there is a pin that extends out from the back of the tractor you pull on and insert a clip in to enable it. I pull out the twig and all is right with the world. Nerxt time you say to yourself "You know, if I had bad luck this could happen", stop and resolve it.