Replacement of 24i fan?

i had trouble with it a month or two ago, the upshot being that a 'new' fan was installed. i always thought it was an old one the gas fitter had knocking about as he didn't charge me for that particular item (long story), it was noisy as hell. anyway last night it packed up, burnt out. it wants to turn , i can hear it.

it looks like an easy job - just take it out and replace. but is it?

boiler - worcester bosch 24i