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
[email protected]
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 Sarangan  wrote:
>
>> Probably the blockage has moved further downstream, and into the
>> vacuum solenoid. Try removing the solenoid and cleaning it.