Downloading Old Podcasts

I have subscribed to a potcast that has 280+ episodes. I cannot get podtrapper to download the headers of any past the last 100. I have gone online to view all the episodes and I would lilke to get out a few that seem to be out of reach. I have found a way to do it manually, but this is very laborious and makes it not worth the effort. Is there a more automated way to get out these older broadcasts? 
