I have lots of experience with Eperspachers.
Firstly the primary cause of poor starting is low voltage, and for an eperspacher that can mean anything beloe 12.5V
Secondly the next one is fuel starvation, but as yours never initiates a firing sequence ( ie are you getting pump pulsing). I find that after disconnectng the fuel it can take 4-6 restarts to get going, I often pull the fuel tube out of the burner, get a start sequence, wait till it spurts out and stuff the hose into the burner again.
Some models of Eperspacher had a lockout after 5 or 10 times, However it was only to my understanding out into the Hydronic units not the Air units, ( but there is a bog internet
discussion somewhere about lockouts).. My understanding is that the lockout prevents any further operation, so it doesnt sound like yours. All the newer Epserspacher units dont have lockouts.
Unfortunately to clear the locakup and resume you need the Eberspacher Programmer. ( or the dedicted service tool). The programmer can be got on ebay for about 40 $ it connects up into the diagnostic wire, and can read the fault status of teh controller and reset the lockout.
However in your case I'd suspect the controller might be faulty.
IN my experience Epers are simply to fix but you do need an understanding of it and some bits and pieces, they mainly fail from lack of use.