Any ideas what a gritty metallic substance in the expression pneumatics
in my Welte Licensee can be?  That's the pneumatic governor, i.e., one
either side.  It's not dust but very gritty.  Obviously it seems to
have been pulled through the system, i.e., from the stack.  Are the
valves disintegrating?  Where could this be coming from?  It's on
both sides and I don't want to connect up the newly recovered and
rebuilt expression shelf and pump and then fill it up with this debris.

If it is the valves, any suggestions on what can be done?  Having
examined the stack, the stack was rebuilt by the previous owner and
he seems to have done a good job, good cloth and hot glue.  He was not
forthcoming about the valves and I have yet to take it all apart.

There are so very few Licensee Weltes in the UK and I have no contact
over here on this side of the big pond.

Jonathan Holmes
United Kingdom