Any chance it's one of the gimbal pins?
Item 40 is parts diagram below:
https://www.marlow-hunter.com/wp-content/export/Vendor-Manuals/Seaward%20Princess%20Stove.pdf
Item 40 is parts diagram below:
https://www.marlow-hunter.com/wp-content/export/Vendor-Manuals/Seaward%20Princess%20Stove.pdf