#2 pto speed inop

hi i just purchased a 1978 b7100 4x4 with a brush hog and a tiller i brought it home and started going over things first i had to order new hubs for the rear axle way sloppy then started checking out all functions and determined that#2pto speed is inop #1 and #3 work but no #2 i have not ran any implements yet but still believe #2 is broke no drive when tractor is idleing in #2 pto and has drive on #1 and #3 at idle what could be wrong and what do i need to do to check it out your help will be appreciated . also what will it take to get and install a frontend loader onto this unit i see that there are plans avaible to build your own loader please help this is my first tractor

maybe not but it still would be nice to know that it does work/I'm just trying to determine how big a job it will be to first troubleshoot then repair it . how much did it cost you to build the loader i see new loaders cost as much as i paid for the tractor with the implements .