Jay,

I have NH565, never experienced this problem with it; however it sounds like one or more of the glow plugs are burnt out.  If you can do resistance (ohms) test; this is where I don't know what the reading should be.   I would guess there should be a reading of less than 1 ohm, but greater than 0; these are similar to my GMC diesel.  NH should be able to give you exact readings, and if your are higher, yours should be good.  To do the test leave loader key off, try to remove the wire running to the glow plug and test on the plug to ground.  If you would like I can go test mine to give you a benchmark reading.

Don