I must have changed hundreds of those TO100 can 741's in equipment, as the application they were in abused the offset null as a way to trim the system offsets, not the opamp offset only. This would invariably lead to parameter shifts in the opamp offset, and the cure ( aside from redesign to get the offset away properly) in most cases was to simply replace the stressed opamp with a new one with less stress in it. I tended to simply take the board and set the offset to zero with input shorted ( thank you for the manufacturer making extender cards with links on them, and with each link having the ability to either be through or open, using little U shaped jumpers that would accept test leads, and also for putting spare sockets both sides so you could probe there or use as grounding jumpers for the inputs. All aC signals with synchronous rectifiers, using a lot of older DG series analogue switches, discrete JFET switches, Unijunction transistors and such to do sample and holds that acted as rectifiers as well, then into an 18 bit ADC for digitisation into a serial data stream into some MK4007 serial memories, 1026 bits of CCD storage for everything, all recirculated once per cycle for operation.