The Scammell Roller Shutter door 

The roller shutter door on the back of the box trailer has never been easy to open, lubrication can work against its smooth action.

Old oil congeals with age and becomes more like  a glue.

The door was dismantled last year and all the old grease removed.

It worked better  but still required a lot of effort to push it up and pull it down.

I decided to look closer at how the slats behaved and it was clear that they operate like a chain and follow the the running groove with  flexibility.

Standing inside the unit with a torch i could see that the bottom part of the door was rigid and that shouldn't be.

The slats at the bottom had been replaced, after taking off an original i compared the two i noticed that it had been made 2mm extra in height.

This caused the slats to bind together to become rigid

I reworked the replacement slats to size hoping this would free the door up.

They were sanded down and repainted one slat had some rot in it so a bit of slicing in was needed