do I always have to use P*.* after a G42? Mach does not see to get radius from tool table. When I input radius into code program runs fine. Tool length comp is working right but not radius.

You can use:
G42 (which uses the radius in the tool table of the current tool)
G42 Dx (which uses the radius in the tool table of tool x)
G42 Px.xx (which uses the specified radius)

just putting a G42 in the program does not seem to work. The tool length offset works good but not radius. So that at least tells me that my tool table is correct. I have had to use G42 Px.xx to get it to work. Have been reading quite a few other posts and maybe I have not had enough lead in. Just wanted to make sure there was not a check box somewhere that I had in the wrong state.

If you are just using the G41/42 (without the P?.?), I think you need to have a tool change (M06 T??) in your program prior to the G41/42.  Without that, the software doesn't know what tool table entry to use.

I just did some playing and found the following:

G41/42 without the P?.? parameter and no active tool (Tool 0) - It appears that the entry for Tool 1 in the tool table is used.

G41/42 without the P?.? parameter and preceded with a tool change (M06 Txx) - The tool table entry for Tool xx is used.