Problems reinstalling the analytical head on a Agilent HP1200 series autosampler after replacing the metering seal

Hi Kevin,

Here is the link to the older LC maintenance videos which includes the metering head replacement:  http://www.chem.agilent.com/cag/cabu/lcvideoindex.asp

It is located under Well-plate Sampler & Micro Well-plate Sampler  and  Metering Seal and Plunger.

Once you tell the software or handheld to change piston, the metering plunger should be flush. Could you send a picture of the drive without the metering head?  You are correct that it should be that simple. 

Probably the position of the motor is too far out so the backplate of the piston is in the way before the head reaches the casing..

You might be able to drive the motor back with the "Maintenance Positions" tool in Lab Advisor. Get the latest version here: http://labadvisor.pl29.agilent.com/latest

The metal ball you are seing in the drive photo is sitting on top of a spindle which is connected to a motor.

This metal ball presses at the backplate of the saphire piston which is pushed against the ball via the spring seen in your second last photo.. The piston is visible though the spring..

You might also be able to press the head against the drive so the backplate is pushed into the head / piston moves into the head and the spring compresses and you are able to put in the screws while still pressing the head in against the spring..

You can press in the backplate by hand against the spring tension, it´s not that hard, but be careful as applying any off-axis force might break the saphire piston.