suggest MAC powercables...inexpensive and make a big improvement.
offers a unique item,
"Clearview Double Helix Power Cord Kit" that you splice onto your chopped short (by brave you) existing pigtail of a permanently attached power cord.
You can call or email the company to find out the real world results of this idea which lets a bit of the original puny vintage cord remain.
I use their power cords and power strips, but never had the courage to chop short a built in AC cord, although none of my permanently attached cords are as rudimentary or needy as what you describe.
Just use an adapter. it plugs into the stock cord, and has the IEC connection on the other end.
Many places offer them... VA Audio for example, or Google for IEC adapters. Online power, I think supplies these too, singles and doubles. I've used and have both the VA Audio adapter, ($15) AND THE oNLINE ONES ($3 - $6), THE DIFF IS SO SMALL IF ANY, i BOUGHT SEVERAL MORE OF THE CHEAPER ONES TO KEEP AROUND FOR BURNING IN POWER CABLES OR TO USE WITH GBETTER POWER CABLES ON NON MIGRATORY CORDS... EX. CABLE BOX, cd CAROSEL, tv... ETC.
If used solely to CONVERT, say from a 20A IEC TO a 15A IEC, or vice versa, Voodoo Cable offers some fine ones right here on the 'gone.
FYI, sounds like you no longer have the OEM / stock power cord that was shipped with the amp.
I've owned two pairs of the Forte 4's and they all had 3 prong AC cords, some hardwired some IEC plugs.
If the unit you have is only a 2 prong AC cord ... STOP USING IT... and verify that it is correctly wired (hot/neutral + ground?). Apparently someone has altered the amp and it may no longer be safe to use in your home.
AC line voltages are lethal when mis-wired. ---WTTW---