I would like to replace the power cord on a vintage 1940s Hamlton Beach malt mixer, and the only access is from under the base.. The mixer is in mint condition. However, the metal base plate is mounted to the bottom of the cast iron mixeer with four screws through the four rubber feet. The screw heads are approximately 3/16" in diameer and are completely corroded/rusted. The base of the mixer is a commercial model that was probably useed at a soda fountain and was probably subjected to plenty of liquids over the years.
I have tried to gently unscrew all of the screws but they are definitely "frozen" in place. I'm afraid if I apply too much torque that the screws or even the shafts might break off.
I haven'tried using penetrating oil yet, mainly because the screw heads are somewhat recessed into the rubber feet.
I would appreciate any suggestions for removing these screws either with penetrating oil or by some other method. Because they are recessed it would be virually impossible to grasp the screws by any other method I can think of.
All reasonaaable commens welcome.
TIA