Not starting first time anymore after fiddling with filters

[rosss]

Hello!
As the title suggests, my bongo, which has started first time every time since i bought it three years ago, has stopped starting first time.
If it's cold it might not start, or it needs to be revved to get it to start. Once the engine's warm it's fine again.
I've seen a few similar threads where people suggested to look at the glow plugs.

The thing is that it started happening precisely on the day when i changed the fuel filter and messed about trying (and failing) to get the banjo filter out, so it seems to me that it's something to do with what i did. Fuel not getting through so easily now maybe.
I'm wondering if the problem could be that i introduced an air bubble somewhere in the fuel lines... maybe in the banjo filter bit...
Any way i can check this?

All thoughts appreciated...!
Thanks.

[g8dhe]

It could also be a problem with the Glowplugs ? Perhaps the rail got dinged whilst working on it and you have blown the fusible link? Check that you are getting volts to the rail that connects the plugs together.