Welcome to the Raymarine Technical Forum Tim,
Raymarine does not separately sell the captured screws for the radome top covers. The captured screws are included with the radome top covers.
The RD418HD and RD418D Case Seal part number is R58232
The RD418HD and RD418D Top Cover part number is R58229. The Top Cover includes the case seal and pre-installed captured screws.
The captured nuts found within the radome base and cannot be purchased separately from Raymarine. The part number for the RD418D/RD418HD Radome Base is R91245 and includes the captured nuts.
I need to replace the insides of my radar RD418HD and don't need to replace the cover.
is their a part number for this?
Thank you for your help. Mark