Solex Pict 34 5 refurb for 1.9 DF

[nicktennear]

So the PO bought a Pict 34 4 to replace the 5, not sure if this was deliberate or a mistake, but the guy he paid to put it in has got it in but at idle it feels like there's a vacuum issue. The original 5 came with the van and I've looked it over and it seems ok but the vacuum unit ( 070 129 102) looks a bit battered. My plan is to get a refurb kit but if the vacuum unit is kaput could I reuse the one from the 4? It's a different part number but is it essentially the same. Plus, why is it on the end of an arm into the main body?.I've attached pictures of the questionable 5 if anyone can spot anything amiss. Cheers all