Slide a hacksaw blade up the centre of it and nip the bolts up onto it. This will buy you a couple of thou more to get the rail in place.
Johno will of made it to fit a 900 but there are tolerances on everything so yours may just be a thou bigger than johnos test block.
Being a 19 mm riser you may not have the same slot in it that you have in the 40mm riser, so you may not be able to do the above.
If you bought it from Johno return it and he will sort it.
Last edited by Marmitinator; 4th July 2016 at 03:48 AM.