Plastic spacer for Marshall windows

Hello,
I am trying to source replacement parts for my Marshall windows as follows:

1- they have sweep locks and they seem to be fine, but there is a plastic spacer underneath the lock that is falling apart due to sun and heat exposure. Do the locks on your site - #90-005 would be the one I think - have this plastic spacer underneath or is that a separate part?
2 - we have a plastic spacer on one side of the window - these are cracked and broken wich keeps us from opening and closing the window properly. Is it possible to replace these? The windows do not tilt and are perfectly fine in other ways.

Thanks so much in advance for your assistance!
Kathy

Hi Dave,
It seems to be plastic that inserts into the top of the window frame and serves to be a place for the screws to tighten into. They sit inside the metal lock mechanism and are about 2 3/4" x 1/2" (Pics attached)

I have also included pictures of the side spacer that is also broken. They are black plastic and have cracked and split - hopefully the pictures can show them clearly...

Thanks for your help!