3TB Seagate Barracuda Upgrade - ST3000DM001

Hello there fellow tinkers, here is my problem:

TimeCapsule A1254 500GB (Original) Upgrading to 3TB HDD.

Facts:

Works perfectly Well with the original 500GB Seagate ST3500xxxx.

Tested with 3TB Seagate and 1TB Seagate HDDs. TC will power for exactly 20 or so seconds, and will shut itself down.

If old Seagate HDD comes back in, works just fine/detectable by airport utility, etc.

I have done 3 of those upgrades thus far, never have had an issue, only thing I can't remember is that I think I was using WD HDDs vs Seagate. Just got a good deal on Seagate ones from Tiger Direct. :-)

Difference between drives:

Original: +5 V0.72A, and +12V 0.52A

New Ones: +5V 0.75A, and +12 0.75A (Both 1TB and 3TB HDDs)

So, bit of a difference there on the 12V bit, with 0.23A (230ma) difference.

So, am I hosed? :-) I haven't done the upgrade like this in about a year, or so, but never had an issue, actually I think WD HDs were drawing a bit less power overall than Seagates, but not by much.

Wondering if I go with tinkering with power supply, admittedly this one is an older one; I took a look at the PS, and it looks pretty good, no bulging caps, nothing of the sort that would suggest failure. But, one never knows...

Any thoughts?