Been there done that .
Do not take any short cuts .
Completely disassemble the roller and remove boiler from chassis .
Some of those screws look dodgy and non original .
And while the boiler is out remove the screws and also in my opinion unsolder the ring from the boiler as it is a weak spot on their boilers . Flatten the edges to get a good solder .
Any more help just ask .
I have had more than 1 wilesco here to repair boiler
Cheers
Dennis