3/5 hole punch P/Js

[Lagonda]

G'day guys,
We have a SR3020 finisher that is running a 3hole /5 hole type 3260 hole punch.

When the customer is printing booklets (A4 short edge first) she is getting intermittant jams in the punch unit. As the paper has been duplexed it tends to have a slight downwards curl on it and this is enough for the rear leading corner to catch in the rear most punch hole.
Its very intermittant but very annoying. ( yes, we have tried different paper and inverting the ream in the tray but didn't make any apreciable difference)
Have swapped punch units but no luck.
Anybody got any ideas?

[Fearless V K]

You may be able to reduce the paper curl by increasing fusing pressure (nip bandwidth) or adjusting the temp. If moisture in the paper is a problem, consider a tray heater.