Paslode Nail Gun Spark Advice

[JBASport]

I have had some intermittent firing with my Paslode IM65 Nail Gun. I stripped it down and gave it a good clean & oiling. Before I completely reassembled it , I thought I would check the spark. I noticed that although it sparked on every trigger operation, sometimes the spark arced between the tip and the lug above it, but often the sparked would arc horizontally to the case. Is this normal only I cannot seem to find any detailed information on troubleshooting & sevicing Paslode Nail Guns. Thanks