If anyone needs any assistance for their Martin Baker series ejection seat in a jet warbird either static or flying, i recommend trying the excellent British firm SES -
www.ses-safety.com they will be able to hopefully supply MB seat parts you need for a overhaul and at a good price.
They helped me in Australia with support for restoring my Martin Baker H7 series F-4D Phantom ejection seat this year.
(For those playing at home, ejection seats dont come cheap. You can spend up to $10,000 in some cases restoring etc.)
Phil