Jia, I'm not familiar with this particular Laurel unit, but most spinners have a vacuum interlock switch that prevents spinning if there is insufficient vacuum at the chuck. This can often get stuck if photoresist gets down the shaft. If your switch is making partial contact, it could explain some of the symptoms that you are seeing. I would look for this interlock switch and clean it just as you did the solenoid. Brad Cantos brad.cantos@holage.com http://holage.com On 9 Dec 2010, at 9:32 AM, Jia Yao wrote: > Thank you Andrew for your suggestion. I have taken the parts out and had > them cleaned but still it shows insufficient vaccum value v~6 or 7. What > else could I possibly check? Thank you! > > On Thu, Dec 9, 2010 at 9:03 AM, Andrew Saranganwrote: > >> Probably the blockage has moved further downstream, and into the >> vacuum solenoid. Try removing the solenoid and cleaning it.