If im correct yours would have originally has 2 different test leads .
Later on they put the a switch in the probe so that you could select the 1 meg resistor for measuring DC voltages .
Mine is the model newer , made about 1962 .
looks like this one
Personally , I did not like the switching type probe , and I prefer the 2 inividal main probes .
I found that the switching one was fat , and was not all that easy to get into tight spaces . , and somtime the switch gets bumped
You can use a regular probe for the DC measurement but you need the 1 meg resistor in it .
Once you get them all fixed up the Heathkit VTVM's are really a great instument , and are one of the most handy items on the bench .
Please note , If you make a DC lead , be sure that you put the 1 MEG resistor at the probe tip , not at the plug end as this will cause you to have false DC readings .
I think I have some probe & lead , wiring info , I'll post in up tommarow ...