Beth,
I have seen many responses to your inquiry but have not seen where anyone
uses a cryostat that has two temperature controls. My Zeiss has a chamber
control and a block control. I can set the temps independently. Sometimes
the guide plate (plastic) gets warm, but my magnetic blades never seem to
need cooling down. When I do "fat" tissue I set the chamber to -25 and the
chuck to -30. It works fine even with my hot little hands in the chamber
since only the chamber feels my warmth, not the block. This may not be a
solution to your problem but people who do a lot of fat tissue might want to
keep it in mind when the time comes to purchase a new cryostat. I am sure
other vendors have what is sometimes referred to as a "research cryostat".
anita