Railway Forum - correct part number

Hi,

My son needs a new wheel/axel set for his Hornby Thomas train. He has ruined the plastic teeth on the middle axel cog.

I downloaded the service sheet from the Hornby website only to find there are several model numbers for Thomas. I need the correct model number inm order to buy the correct parts.

Ali's Thomas was 2nd hand so I don't have the box that would show the model number. Is there anyway to tell from the engine what the model number would be?

The parts I need are either X8873B, X8874B or X8871.

All I have from the engine is a 2006 copyright and S4581. There are cooper pick up points on all 6 wheels.

Any help appreciated. I have also emailed Hornby but was hoping someone on here may be able to help quicker as Ali wants his Thomas back.

Alex