Weber DFH4 secondary Diaphragm device service

[laverdaas1]

Hi there, i'm servicing the WEBER DHF4 carburetor on my on my 124AS. The diaphragm on the secondary device would worth replacement while, for whatever reason, the spring in it is missing any recommendation on where to find them? for the latter any clue of its dimensions and spring constant just to try find something that could do the job? thanks