Thanks for all the replies - much appreciated. The lamp is a Philips 13139 and it appears to be fitted correctly. I assume it's the right holder too but I might need to google more pics to be sure. Am now using 5.6 (with 20 Magenta) but still with 60 sec + times. No big deal - in fact it's nice to have more time to dodge and burn, but it seems a long time compared to what I am used to. I might look into sourcing a new lamp just in case that it the issue.