Good friend of mine worked down at the Cape for NASA. His job...weld the titanium heat shields for the shuttle. He would "warm up" for the task by welding a couple Juicy Fruit gum wrappers together. Of course with a high frequency machine. Not to drift off topic, but in alot of cases, the answer is yes
My welding instructor was an active contractor for NASA who welded parts in vacuum containment with micro laser welders. (One day he said he got a new welding "toy" for an upcoming contract work ... mere $35,000
and I thought Miller machines were expensive).
When we got our graduation certificates, he goes, "Don't get cocky with your welding certification" and cut an aluminum soda can in half then welded them back together. When our jaws dropped, he reached for two stainless razor blades and welded them together.
Of course we went, "We are not worthy ... We are not worthy"
He told us to never stop learning/practicing and strive towards his level of competency. (I should use that to justify a new multifunction TIG/plasma cutter machine to wife ... "But my instructor said to never stop learning ... And I am a lifelong student ... Like shooting and reloading and cooking" ... After making me
bake all bread/rolls/cake/cookies now for retirement, she now wants me to make crossiants ... Yes, 163 layers! Oh my.
)
During class, when I was filling a dime sized hole for neighbor's engine head surfacing machine cover, I layered Mig welding wire on top of each other to fill the hole. Instructor was impressed as he never seen that done and said, "Neat, waste of welding wire but neat" and smiled.
As to repair of "cracked" RCBS press, we haven't heard back from OP
@74man as to whether the press is made of cast iron or aluminum. As many members posted, repair of either materials will heavily depend on the skill level and equipment at hand.
But I still think a call to customer service is the first logical step before any repair "attempt" is made as you never know, RCBS may offer new replacement for "cracked" press, at the worst possibly with discount.