Pioneer 2073 chain adjustment?

[Phil13]

Hi all, just bought a Pioneer 2073 and got delivered last night. Not had much of a chance to look at it but was assured it was a runner? What I did quickly spot was the lack of chain adjuster? I guess there's a tool of some kind for adjusting? There may be something missing! but on the clutch cover all I can see is a metal plate that looks like it's spring tensioned and when in place it has a hole that lines up with the hole in the bar. Any advice greatly appreciated.
Many thanks Phil