This isn't a hard one at all. It's exactly the same as the one from yesterday. Just ignore the red herring information, and realise that you're at 675', QNH=1000mb, and altimeter sub-scale is set to 994mb. Everything else is irrelevant.
The altimeter is 6mb out, 6mbx27ft/mb = 162'. The sub-scale is set low this time, so the altimeter will under-read by 162'. Answer: 675'-162' = 513'.
Do I get the prize this time? I promise that if it's champagne I will spray it liberally over everyone!
FFF
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Edit - Monocock beat me to it, by 1 minute. But since I described how I got my answer, and he didn't, I still think I should claim the prize!