1-1/8" Nestbox opening for Tree Swallow MI (1 Viewer)

I was reading online that to keep out HS you need 1-1/8" hole in the nest box for Tree Swallows? Having a terrible time with HS. Tried the 1-1/8" new hole opening over the old hole. Haven't seen the HS after doing this. Just hope the Tree Swallows con fit in the smaller opening. They are only hanging around he nest box, not going in side. Any thoughts!:h?::

I think 1-1/8" may be too small for a Tree Swallow. The recommendation I've seen is 1.25?-1.5". And 1.25 is tight even for a Black-capped Chickadee.