Gear lever sticking

[racetek]

I have a MK2 with a 4 synchro box from an S type. I have a strange issue with 1st and 2nd gear. It works fine when first started but once the engine and gearbox are warmed up, usually after a long run, it is almost impossible to select either 1st or 2nd gear. There is no gear crunching its just that the lever won't move. When slowing down I can select second by matching the revs on the downshift from third, but once stationery it won't go into gear. It will go into 3rd and 4th. Seems like a selector issue but thought I would check here before I start pulling it apart.