It sounds like your data source is a delimited file, perhaps space delimited? , with quotation marks around any text values - or are all field in quotation marks?
Are you reading it as a REPORT or importing it as a DATABASE?
If it is a delimited file it may be a good idea to import it as a database since that will provide you with all the control available for both the delimit character and dealing with the quotation marks.
Go to the HELP INDEX and look for SAMPLE. Under that is DATA SCREEN, which should tell you what you need to know.
If the data is delimited and therefore column widths are not consistent use the method above.
But if the data is in fixed columns but still quoted you may have other options for using the file like a report. You would need to work around the quote marks in the model OR more likely use the Monarch Utility to prepare the file before trying to process it.
I hope this helps.