Clovis,
Your bike is a 2010-2012 Multistrada S model correct?
If so those have a bit different bits in them than more normal type Ohlins forks.
First they have servo's inside to activate the valving on the fly.
The left is compression and the right is rebound, this is how they adjust to the different modes.
I would also be very careful as the electrical connectors on top are extremely fragile, so beware when disconnecting.
I would find a shop to take or send the forks to, removing & installing them my self.
The seals and or bushing aren't really the issue, it's the packaging that if assembled incorrectly, could not give the correct performance, or worse.
Just my thoughts on this matter.