Tim:
This is my 66th year of keeping bees, over 100 colonies for most of those
years.

Never have I seen inner covers STUCK DOWN.

Are you SURE that you are providing the bees with enough super space?  Bees
only build burr comb on frame tops if they are short of super space.  If your
experience
indicate that your colonies normally produce 3 supers in spring by July 4th,
they should have at least 4 and preferably 5 supers in place on the colony by
about May 1st for PA.

See some of my writings about this.  Older writings are on
http://www.cybertours.com/~midnitebee/     click the lower right image
Newer writings are on
http://www.beekeeper.org/george_imirie/index.html

I despise Plastic!              Hope I have helped.     George Imirie