Black & Decker DN710 Blade change help

[KraftyKev]

Hi Folks.
Sorry about the large Image..

Never changed a Planer blade before and thought it an easy task.
Old Black & Decker DN710
Got a pack of 2 new Blades from Screwfix 82x10mm
Removd the outer cover.
Loosened the 2 Blade securing screws but when I fitted the new blade and tightened the 2 screws the blade remains loose.
Suggestions please as to what I'm doing wrong.
Tried to install an old blade to see if the new ones were thinner but they won't tightenen either.

 

[MARK.B.]

Try cleaning out the screw holes and wire brush the threads on the screws

 

[Bingy man]

Any chance that you have cross threaded the screws, how did they feel when you replaced them , hopefully it’s as mark b suggested and just rubbish in the holes .

 

[KraftyKev]

All clean and free, Screws tighten down nicely its just the plate they screw down that pinches the Blades is not pinching them.
The image doesn't show the plate that goes over the top and that has 3 screws securing it and I wonder if that is meant to pinch the blades, I will try again Sunday..
Thanks for the reply Guys, Appreciated ...