It probabaly is just dirty. Mcintosh uses 1/4 glass and it is not a laminated safety glass when it breaks it cracks, not shatter. To replace I recommend calling Mcintosh and order a service manual and expect to pay about 15.00 and then you can see if it is just in need of cleaning or replacement. Becarfull not to wipe the ink off the inside when cleaning. I have had a few Mc peices that I have replaced bulbs on and they are little time consuming to get apart but not undoable if you have ever torn a toaser apart. The manual's exploded veiw helps a bunch on this.