Parking break on my XK 150 FHC has stuck in full up position. Thoughts on how to release? Do i need to remove passenger seat - if so how is that done?

 

Have you tried a lubricant spray into the handle? Also at the base where the catch is. Move seat forward reveals bolts in rear rail and then move back to get front bolts. Will give you access to full handle. Might check under car for rusted cables to rear of car.