Drive belt pulley help needed!

[doctle]

Hi guys,
I'm stuck again! When cleaning the engine I noticed a flat spot on the drive belt pulley, seems it's a stretch belt on this car so no bolt off tensioner (thanks for the copy and paste Haynes) I want to change the pulley there's no clearance between the pulley and the chassis rail so how does it come off? Do I have to take off the exhaust and engine mount and lower the engine? I assume it's a hex drive I can't see.

If anyone is interested I found the glow plug relay it's under the headlight I can't get my hand in so I need to remove the bumper to remove the headlight to check/replace a relay, Seems a poor design to me!