Note there are 2 variants of the PHM slide – early and current, the current slides part number will have to be modified to fit the early carburettors.
The important difference is the width of the stop screw ramp – please see picture:-
p/n 8639 Ramp slide 4.45mm wide
p/n 11815 Ramp slide 6.2mm wide
Please measure your existing slides before purchasing a replacement.