Main fan as fitted to our Top Hatch machines from 5TTH downwards

The fan is an easy like-for-like replacement task for a moderately competent person

These fans are ball-bearing fans and they are rated for 10 years of continuous running in a hot environment.

Their two main causes of failure are damage by the heaters close-by and deterioration in the off-season.
The Fan switch is provided for troubleshooting, in case one of the three fans fails. The FAN switch must always be on. 
And if stored in a damp environment for the off-season, turn the machine on regularly to warm it up and dry the electrics.