Rotor3D+ inpower crankset

[Andy_G]

Hi.
I'm trying to install one on a R5 cervelo, but for the life of me the left arm won't go through, it goes in a mm or 2 and then stops dead with no signs of anything stopping it, it's the correct BBright 4630 BB.

Any ideas

Thanks

 

[Milkfloat]

Grease and a rubber mallet. Assuming it is lined up.