Peavey classic 50/50 keeps blowing fuses.

Question

I put new gt el84 power tubes in my peavey classic 50/50. It ran fine for a couple days and then started blowing fuses. Now when I turn it on it hums very loud for a second or 2 then pops the fuse. Did I Blow the power OT by not rebiasing the amp. Any Info would be nice.

                                         Thanks
                                            Rob