I did a leak check on conditioning station vacuum system today.The vacuum system had been roughed over night . This morning before the leak check,the convectron gauge  reading on emittance box is 20m torr which is reasonable. I hooked the  leak detector to system (without turbo pump  on) . The leak detector showed base LR 6.3xE-8 atm.cc/sec. At this base LR, I found 2 leaks up to low E -6range on that cross tube flange to small turbo pump, and the cross tube flange to vessel. I found some of the bolts on the flanges could be tightened more ½ to ¾ turn without difficulty. I checked all the fasteners on the box, cross tube, and turbo pump, tightened some of them. By doing it, the base leak rate dropped to 3.0x E-8 atm,cc/sec, base pressure still 0.0XE-4 torr. I sprayed helium again, the response I found before now disappeared. I waited for about 1hour, and let the leak detector base leak rate dropped to 1.3 xE-8 atm.cc/sec, and base pressure still at 0.0xE-4 torr. At the same time, i only use leak detector as back up pump for whole sysytem and shut off the valve to the scroll pump.By doing this , the leak detector is much stable on the base leak rate. With the help of Bevan, i sprayed the helium to all the vacuum  equipments again.This time,no any tiny response has been found on leak detector.The leak rate stayed at 1.2x E-8atm.cc/sec, and no change on pressure also. I checked helium bubble several times during the spray. The conditioning station vacuum system is leak tight.