These are things that will affect the amount of crema you will end up with...
* Freshness of beans (1-3 weeks optimal)
*Time between grinding and brewing (same day MAX 10secs - 3 mins optimal)
*Dose and tamp (dont forget ambient temps will affect this also)
*Water pressure (too low and the creme will be thin)
*Coffee fairies (good to blame if you cant find anything else I had a laugh)
These are the main things i would look at to start with followed closely by machine cleanlyness. When was the last time you back flushed your machine with a proper chemical? Im doubting its the water temps as you would have noted it wasnt as hot as it has been?
Good luck and if all else fails? Pack it down and buy a new setup! That fixes EVERYTHING ;D Momentarily :P