How to uninstall Rumba TOTALLY - re-install of 9.5.1 crashes

I have a 10.1 installation including a (test) 64-bit Rumba Addon.  There were some issues with this when testing.  Now I saw that even using previous version of our software code (which when built with 9.5.1 libraries *does* work properly on servers that have 10.1 installed), when debugging I am unable to connect to the Mainframe (TN3270).

So, I uninstalled 10.1 (this was in 2 steps - the Add-On and the main product; during the Add-On uninstall I *did* see an error, which I unfortunately didn't do a screen-save of :-( ).

I then freshly installed 9.5.1 along with SP1.  I still crash, in what appears to be the first (attempted) usage of the Rumba add-in.  In particular in debugger I cannot get past the following line:

With frmHostInterface.HostDisplay.HostInterface
.Name = "WallData.TN3270Link"
.Interface.InsertName(Name:=mvarIPAddress, RetCode:=returnVal)
If mvarPort <> 23 Then
.Interface.TelnetPort = mvarPort
End If
If mvarLUName <> "" Then .Interface.DeviceName = mvarLUName
.Interface.Response = True
.AutoConnect = "1"
End With

I suspect that there is something left over (file, or more likely registry entry/old or 10.1 OCX registration?) that never got totally cleaned when I uninstalled 10.1.

Any advice (other than format C: ;-) ) on how to totally clean 10.1 installed (and maybe also 9.5.1 install - I am will to -reinstall 9.5.1 from scratch) - would be most appreciated.  I did do reboots in between in-installs and installs...