How to fix a toilet handle that won't come back up after flushing?

I have a Mansfield toilet. The flush handle broke off, so I bought and installed a replacement handle and lever. It was difficult to get the lever through the loop on the flush valve (the toilet uses a Mansfield flush valve rather than a conventional chain). Now the toilet will flush, but you have to manually push the handle back up afterwards to stop it from continuing to flush. Does anyone know how to fix this? Thanks.