AGA Going out after 12 to 36 hours

[Taffaway]

Have a problem with an oil fired AGA conversion
Has been no problem for 5 years, now goes out 12 to 36 hours after lighting, have checked fire valve, and have installed seperate line from tank to feed AGA
went for 3 weeks one time, then went out due high winds. Has now started same pattern
Help, losing what liteel hair I have left

 

[Best]

Do you have the Aga properly serviced? Maybe stating the obvious points but my first thought would be the steel pipe feeding the Aga burner gradually narrows with carbon & has to be carefully cleaned, literally drilled out each yearly service. The wicks not as important, but need to be replaced on servicing.
If it ain’t burning properly, perhaps weakly, due to partially blocked flow rate, then windy weather could put the flame out.