Extracting filename to custom properties

I've spent a few hours on this forum trying to learn how to create a Macro to extract from the file name and import the info into the relevant custom properties. I have no knowledge with macros but have tried to pick up some things as I go along so I apologise if this is really basic.

I've succeded in extracting the necessary info into the DWG No. and Description fields.

Only issue I currently have is that for the description, it keeps including the ".SLDPRT" or ".SLDASM"

I've tried a few methods to instruct it to replace it with nothing but I keep getting errors?

On the Macro so far, the description section is:

    If swModel.CustomInfo("DWG No.") = "" Then

      swModel.AddCustomInfo2 "DWG No.", swCustomInfoText, Left(swModel.GetTitle, 11)

    Else

        swModel.CustomInfo("DWG No.") = Left(swModel.GetTitle, 11)

    End If

What would I have to do to remove the extension from the new custom properties description?

Thanks,

SolidworksApi macros