I have a 26-1K and have been in the dark all day and just noticed your post taking a break. The integrator has a dial that you can turn. If I recall correctly I set mine on the lower number,possibly 2 or 3. I tried to set the dial then turned it on to time it to seconds but it is really not that necessary to have them equal. Just time the units with a watch and write on the front what 100 units is and 200 is etc..You never will have the units stay at the same seconds anyway due to the degredation of the lamp over time. My units are 100=2 min, 200=5min and 300=8 min. Don't worry about having 1000 units=1000 minutes. It ain't gonna happin. Leave the integrator pointing where it was when you took the top off. Hope this helps.
I meant to say that 1000 units will not have to equal 1000 seconds. Sorry for the confusion.