So after reading through this and many other posts here's my summary for those following along:
First, there are two main issues. 1) Sprag clutch failure and 2) belt slippage. (And a third would be rough noises and such from bearing / water damage, typically over time.)
The clutch failure is more common if you have had a lot of hard pedal strikes. This is also easily diagnosed by grinding / clunking noises and the inability for the bike to move backward at all.
The belt slippage seems to be hit and miss as far as when it goes and it's complicated by the fact that we are all talking about different years. It seems that the 2018 and 2019's had a design where this was more common early in their lifespan. Sometime in 2020 Spec / Brose began a newer design that is supposed to be better. There are threads where you can try and identify if you have one of the "good" or "bad" motors based on the serial # of your bike, motor, and ship date. Mine would have been the "good" motor. Regardless, it does seem that even the 2020's have a decent failure rate somewhere north of 2,000 miles.
Because of all of these failures, Spec offered the 4 year transferable warranty in 2020 which goes back to 2018's (maybe earlier?) As such, even non-original owners can get a motor replacement.
This was a great move because Spec wants major market share in the eBike segment and a strong rep and IMHO they are probably putting these things out and letting us do a lot of the testing on them since it's a new and evolving segment. That's how a lot of R&D is done and you just build failure expectancy and support into the warranty and price. It makes me feel good having that 4 year warranty for the cost of these things. I figure it this way; for my money I'm getting a guaranteed 4 year eBike. After that? IDK. It could get expensive or I'll have a really heavy dead DH bike. I guess my point is that at some point these things will be outdated and beyond repair as technology moves forward. The same as any bike but a bit worse since they have the "e" component and overall we are all fairly early on the adoption curve. But for now and while we're within that 4 year window, I already had a battery issue and it was replaced no questions asked. It seems the motor is going to be a similar situation (although there was some talk about a $150 sourcing fee for the replacement motor...we will see.)
Up to this point I've just been smitten with the bike and logging miles and epic rides. I sort of knew the motor would likely go but I also knew I was well covered under warranty so I haven't been giving it much thought. So now that I'll have a new motor the questions on my mind are;
"Do I ride it as much and as hard as I was before and see if I can burn another motor out by Jan of 2024 or do I slow down a bit and try and make it last?"
"Do I start saving for my next one and try and sell this one off for at least something while it's still under warranty in 2022 or 2023?"
"Do I just ride it until it dies and then just try my best to keep it going or scavenge whatever parts from it I can for another / new eBike build?
Anyone else asking themselves these questions?
As for keeping them going after warranty...I have never seen a place to buy a new Brose motor outright but there are places for parts and rebuilds (see below; I even see belt kits etc.!) Batteries are out there for the usual $900-$1000. I used to be a bike mech and I enjoy working on this stuff so maybe I'll just have to get more familiar with them and learn to keep them going. I do think it's the motors and batteries that will be the biggest fail points; consumables really. The rest of the eComponents like ECU's are rarer to fail I think but could be really tough to diagnose in my garage.
Some resources:
Is your motor out of warranty? Are you facing a voided or expired factory warranty and hesitant to invest in a costly replacement? Tired of your eBike motor ...
ebikemotorrepair.com
www.performancelinebearings.com
From noisy motors to diagnosing error codes, we’ve got you covered! Take a look through our services below to find the right option for servicing or repairing your E-Bike Motor.
www.e-motorrepairs.co.uk
And this is THE best video to see the guts of our motors. You can see how direct / hard crank hits and water over time can cause the biggest issues. I wish I could see my belt from my current motor. I wonder if the belt "teeth" are visibly worn on one like mine with the belt slippage issue. I also wonder if we or the shops could be using the belt tension screw adjustment over time as the belt stretches to keep full belt slippage / failure from occurring? There is no easy way to get to that screw with the motor installed and we as owners are not supposed to mess with it but it does make me wonder if this was regularly adjusted if it could help. For those with the sprag clutch issue, that is really easy to see in this video as well:
