Probably not as these are an older model, but does the firmware have a 'Smart IR' option in the image settings?
Sometimes this can dial down the IR a bit much if there is a bright reflective area in the scene.
wittaj - your solution is a good one but at $106 Australian it doesn't make it a worthwhile proposition.
Alistair - Unfortunately it doesn't have that facility.
I have already replaced these three cameras with new types but it seemed such a waste to have them sitting around. They work fine in daylight but poor when the IR is needed.
I guess I will find an application where the IR is not required.