GCMS tuning stopped 5975C

Hi ISH, yes all was fine with column installation and pump down was efficient. The issue seems to be with the entrance lense offset - I loaded a previous tune and managed to run an autotune however it is failing due to too high 503/502 ratio. I've seen some advice that this could be due to HED needing cleaning or a dirty source perhaps? The Ion focus was consistently 90.2 however in the latest tune it is now 71.2 so something is not right this week from last week and previous tunes!

Tune last week had 503/502 ratio of 10.13 where as today it is 13.28. The peak shape of the 502 is also not as neat, slight splitting in the 503 peak and noisier baseline either side.

If anyone has any advice it would be welcome!

Could you please share the tune report? 

I tried to add the tune reports as pdfs but couldn't upload.... Thanks both ISH and paulsalverda for your replies, we got the system second hand so I don't have a 'local' agilent engineer I can call on! I have no experience of removing and cleaning the source of this system but it is looking likely I'll need to. 

The curious thing is that the only difference between the good tune a week prior and the bad tune last week is that I had to vent and clear some debris out of the analyser chamber...I didn't actually touch the source or run any samples so its strange that suddenly the tune has an issue :(  

I tried to add the tune reports as pdfs but couldn't upload.... Thanks both ISH and paulsalverda for your replies, we got the system second hand so I don't have a 'local' agilent engineer I can call on! I have no experience of removing and cleaning the source of this system but it is looking likely I'll need to. 

The curious thing is that the only difference between the good tune a week prior and the bad tune last week is that I had to vent and clear some debris out of the analyser chamber...I didn't actually touch the source or run any samples so its strange that suddenly the tune has an issue :(  

Hi

Just take photo of tune report then you can upload easily..

Did you close vent knob of ms properly?

I don't know but i have a doubt that may be there is leak.

After seeing tuning report, can get idea.

In tune evlauation, what it's showing.

Please make sure that side cover of ms and vent knob is closed properly.

The only thing that failed on the Tune last week was the High ratio of mass 503 to 502....and suggested a dirty source as the potential cause. I was just curious as to why the source would suddenly be dirty as no samples were run and it had passed fine the week before.  

yes vent valve was closed properly - Just to update, today (after leaving the system to settle over the weekend) I have run a Tune and Tune evaluation and it has passed. There are still a high number of peaks in scan section so indicating source could do with a clean but tune portion is now passing. I'm just running a blank to see what the chromatography looks like.