hahaha, I was just editorializing on the state of the aftermarket.
I mean, you have three choices:
1) Call the vendor you purchased them from and work to find a solution.
2) Enlarge the hole with a drill.
3) Use a smaller bolt.
I'd probably lean towards #2 myself but #3 is less work and probably not going to be an issue. Just keep an eye on it.
I wouldn't recommend option #3 because even though the smaller bolt would fit the mount properly and the smaller bolt MIGHT be strong enough for this application, the other hole that the bolt goes through will be larger to accommodate the factory bolt, this will allow movement that could eventually wear out the hole even larger and wear the bolt down as it does so.
If the problem isn't caused by burrs or some other minor restriction, I'd check with the manufacturer first. Drilling the mount so accommodate the factory size bolt would be my first choice if time is a factor. I wouldn't worry too much about keeping the hole centered, the existing hole will act as a guide and help keep the drill centered.
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