Still I wonder if *any* of the Tek 576 relays could be replaced with power Mosfets.
I am curious if some Hexfet / Mosfet relay replacement(s) might then be more reliable ?
Are all of the relays in the Tek 576 that you are referring to susceptible to the issue you have brought up ?
I have used a number of different power Hexfets , Mosfets made by IR ( IRF.com ) , having very low "On" resistances ( 0.0001 Ohms ) at various voltages. These Fets are capable of being turned 'on' via the output of a single TTL gate, without issue. I have also placed these in series or parallel (D-S) to achieve a wider ranges of specification with good results.