It appears that the problems are in the distribution of thermally controlled air and the stability of electronic sensing of the mirror temperature. Several leaks have been fixed. The four primary air-distribution boxes were found to be cold and were subsequently insulated. The Hardpoint load cells were found to be very hot. The source of this heat is difficult to pinpoint and additional work is being done to isolate its cause.
Work continues on both the thermal and electronic sensing system.
Most of the problems seem to be traceable to variable gains on the filter board that is part of the multiplexed readout. This is the principal target for attention early this week. The departure of the mirror from the mirror lab has been delayed until the readout problems are resolved. The primary's surface will be washed on May 12, prior to eyeball inspection through the front plate of the mirror. This will proceed on a non-interventional basis after the surface is clean.