Primary chain tensioner

[Phil C]

Afternoon all. Me again.  Just looking at my (1965 B40F) primary chain tensioner. As you know, it pivots. But the end of the arm seems to scrape on the inside of the casing as it moves (see photo with black arrow to indicate the bit that scrapes the casing.) (Yet there aren't any scrape marks from previous use.) Am I offering it up wrongly somehow? My understanding is that the bracket on the arm end of it (as opposed to the pivot end) sits between the two spacers, which are of equal length. Could anybody advise please? Phil

[Phil C]

Further to my post just now, I'm wondering if,  with my old chain, when I thought the tensioner was at the end of it's travel, it was actually snagging on the casing. Not sure. Anyway, I replaced the chain and now I've noticed this. I'm wondering if I'm not putting the tensioner on right. Should there be a washer or anything?  Phil