The most common problem I have encountered with the Laurell spinners is a sticking valve due to photoresist build up. This valve is outside the body so it is easy to remove and clean. If the valve is not the problem, the vacuum supply itself could be the problem. Failing all that, it could be a blockage in the motor shaft or tubes inside the instrument, or possibly a faulty sensor. Try blowing some nitrogen through the hole. On Thu, Dec 9, 2010 at 12:32 PM, Jia Yaowrote: > 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!