In 2017, when I bought my boat, the boom motor failed.
The engine was running and moving the empty cart but not unfurling the sail.
I took it apart and found that the yellow crown (brass? Bronze?) was completely worn out. The stainless steel worm was in perfect condition.
I couldn't find a workshop to make a custom crown, so I bought an angle gear from Amel (very expensive).
Easy enough to change by yourself.
Conclusion, be careful not to use force to unfurl the sail in a strong wind (release the sheet from the boom before tucking in the sail unfurling line to avoid wearing the crown with the worm screw)