Thanks for the info. My DT50 212 is blowing that fuse under the power chord. I have a DT20 as back up so I used that fuse to test the DT50 and it blew as well. I believe this is the correct fuse as I got the same one (T5AL250V).
I'm about to test the amp with the tubes out to see if the fuse pops, if it doesnt then I'll know the issue is not the transformer but my tubes. If it does however, then the link you shared will be handy :) as I suspect it is a transformer issue. My closest Line 6 dealer is 5 hours away even though I live in the capital of Canada, so that is out for me to just do simple tests.