Hi damian

Not sure if you can buy the gears cheap about $165 from the US and $200 or less for a complete
second hand line trimmer .I would first remove the plastic cutter head completely and make sure that it's
not damaged as the head will be another $20.

https://www.ebay.com.au/itm/M10-x-1...6-FS80-FS85-FR85T-FS86-FS87/333512453156

https://www.ebay.com.au/itm/1928768...XlJSR7wIV74NLBR0LOwS_EAQYASABEgKZpvD_BwE

https://www.ebay.com.au/itm/NEW-OEM...86-80-90-AV-96-106-108-READ/233868960663

Cheers
Max.