Ransomes Certes Mk8 restoration

Hello All, I recently acquired a 16" Ransomes Certes Mk8 which is in surprisingly good condition, apart from the handle not being original (it appears to be from an Ajax) I have started dismantling it for cleaning, and have removed the cutting cylinder today, there is approx 3-4mm play on the bearing housings, should there be any play on these at all? 

Also would anyone be able to confirm the years of manufacture for the Mk8? i'm not having much luck finding details about this

Many Thanks

Jez