As there certainly was produced spares there might have been some logistics to get the goods delivered, however the effort haven't been mentioned much afterwards.
The logistics were as essential for the airbases as for the habours and the advancing armies(*) and was undoubtly performed Somehow and since the airbases did get the food; fuel and ammo they needed, spareparts must have been delivered in the same way.
Anyhow, I have an idea about scrapping parts from worn out aircrafts was one of the mechanics finest abilities and might have kept more planes in the air than actual aknowledged!
(*): Interested in the subject ought to read about the impressive Red Ball Express:
The Red Ball Express Information Page