HI Matt542, and welcome to the community.
Did you transfer your iTunes library over to the new mac? If not, you should because once the Mac recognizes your iPod it is going to delete the music on it unless you have transferred the old library.
Your iPod can only be synced with one iTunes library at a time. If you try to sync it to a new computer/iTunes library the process will erase what is currently on the iPod and replace it with the content that is now in your new iTunes library. If possible, copy your entire iTunes library from your PC to your Mac first. Here are a few ways to do it.
One way to do it is to use your iPod Classic as an external hard drive and copy it that way.
Otherwise, you'll need to use one of the methods described in this Apple support document to copy content from your iPod back to your Mac.
Thank you for your reply , and the welcome ! The itunes library itself was already moved across, I imported it all through home sharing so that is safely on the macbook. I've made that mistake before where I forgot to move the library. So its more a problem I think maybe with the usb connector , or settings I need to change on the macbook , to be honest I thought it would be straight forward to use .