77 GT 4 with a early type 1 . Usual symptoms flickering needle , or nothing , intermittent, or works fine so you tend to leave it . 22 mm metric bolt holds it vertically on the RHS of the gearbox near the fwd bank exhaust pipe . 13 mm holds a wire clamp . In the winter I did just remove it and placed in the airing cupboard for a week .....improvement but gradually the time it does not work was lengthening to exceed the time it worked . Read a few threads on here about disassembly . New part is in excess of £200 . Basically you have to open a factory ( Veglia ) crimp . This was stubborn ....placed it carefully in a vice and with a tiny screw driver acting as a chisel and hammer , worked around the edge of the rim . As you can see the metal is brittle and maybe I was a little ham fisted ....but I managed to open it . The Hall effect wheel was submerged by in oil ! Some oil was splattered on the components them selves. So I used brake cleaner spray to clean it all up . O ring is intact and there was oil either side of it , I have smoothed down the plastic lid and when it’s finished drying in the sun I will resemble using a silicon sealant ..as well as obviously salvaging as much of the damaged crimp as possible . I will put a ring of silicon on the outside of the crimp where it’s meets the body . Unless anyone has any other suggestions to seal it up on reassembly ? Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login There are little key ways on the lid + body = it only reassembles one way .