Don't seem to be able to edit on the new forum. I should have put "one spacer on the drive side" ?

Yes, 1 spacer drive side. But you might find fitting it NDS gives a better chainline, that will work also.

Correct, one 2.5mm spacer on the drive side.

Thanks for the confirmation.

Another question please: The Chisel FS can take a chain line from 52mm to 55mm, according to the manual. I purchased Shimano SLX M7120 cranks (175mm), which come with 2No spacers, each 3mm wide. The cranks have a chain line of 55mm when the spacer is fitted either side. I assume to switch between 52mm and 55mm chain line I just remove/do not fit the 3mm spacer on the drive side of the crank? I have read a few reviews where some people struggled with 55mm chain line and the chain dropping when backpedalling in the lowest gear (50T). Tempted to start with not fitting the drive side crank spacer ? 

I’d use the 3mm spacers either side, but move the 2.5mm BB spacer to the non-drive side like #rockthreegozy suggested. 

You need to fit the axle spacers, otherwise you won't get correct preload

On the M7120 cranks the axle is 6mm longer than M7100 cranks to give you the 55mm chainline. You have to use the 2x 3mm spacers, one each side and the 2.5mm spacer on the DS. M7120 cannot have a 52mm chainline as the axle is longer. If your frame has clearance you could move the spacers around but then your cranks will be off centre.

Update: Fitted with 2mm spacer between frame and BB, on the drive side and the 3mm Shimano crank spacers either side. The crank arm does not fit totally flush on the splines and is about 2 to 3mm proud. Just wondering if removing the 2mm BB spacer (frame is definitely 73mm) would recentre the crank and sit flush fully on the splines, fit the 3mm spacers either side and have a 53mm chain line? Is there really any need for the 2mm BB spacer on a BB52?

Did you lift the hinged bit that's secured on the crank bolts to allow the arm fully on? It's designed to stop the arm falling off but needs to be raised for install..

If it fit flush you wouldn't be able to pre load it. Take a picture and add it here so we can see what you mean. One drive side spacer is normal for a htII BB in a 73mm frame.

As above you should always have a little bit of the crank arm splines showing past the axle to allow for preload, give the drive side crank a good smack with your palm at the axle hole to make sure it's seated, make sure the plastic fin is sticking up on the left arm before sliding into the axle, drive side BB spacer should be 2.5mm, you could switch the bb spacer to the non drive side for a reduced chainline but the cranks will be off centre, not really a problem if using flat pedals, the drive side crank will be closer to the chainstay than the left arm but as long as there's still good clearance it should be fine, I wouldn't mess with 3mm axle spacers, always keep one each side, I wouldn't be doubling them up