Problems in the use of spectrophotometer

In the use of 752 spectrophotometer reading has been very unstable, what can be the reason? -- could be voltage instability-- I don't know, it's always jumping around. Shaojinghua added the following at 18:01 on 2009-11-14. I don't know. Shaojinghua, who has been jumping around all the time, added the following at 18:47 on 2009-11-14. I don't know, I've been jumping around all the time-this may be because it's wet inside or the unitary piece (like a transistor) is broken! Try cleaning the dust off the bulb and wiping it with white gloves to make the bulb stronger. I encountered this problem the other day. B: OK, not today Try it tomorrow-- this one seems to be like this, and my data will jump, and it will still change if you fix it, but it's usually between 0.000 and 0.0002. The repairman said it was normal.-- the desiccant should be changed. Whether the voltage is stable or not-reply "weihua0608", but I use a wide jump range Between 0.0000 and 0.0010-- change the Triode-- the reading of the 752 spectrophotometer has been very unstable. What could be the reason? Shaojinghua was published on 2009-11-14 16:24 752. how does it set to zero? we have bought a model of this model and haven't figured it out yet. Do I have to warm up for 20 minutes? Thank you.-there's a zero knob, the one on the left.