Washing 13x18 cm paper in Paterson washer

Hello all,
I normally print on 18x24cm or larger paper but would like to print a series of smaller 13x18 cm prints,
However, I noticed that this size is too small for the two metal 'arms' of my 24x30 Paterson washer to retain the paper from rising above their respective slots. Did Paterson originally supply any accessories to alleviate this problem? Or alternatively, are there any workarounds?

Thank you

My experience has been that most papers stay below the water surface on their own. For any smaller prints that don't I just position them on either side of the cage, under one of the arms.

If that doesn't work you could put anything that's water proof and doesn't float well on top of the cage . I've used a graduate on its side to do that occasionally.

So far as I know, there were no accessories supplied by Paterson for that.

I have tried using one arm but one corner of the paper always seems to escape from its slot and rise above the water level. I will try placing a small graduate across the slots. Hopefully it will not move too much as the cage rocks.
Any other suggestions most welcome