Ferris FW25 hydro sticking at low speeds

Hi All,

I have a new Ferris FW25 and have noticed that my right hydro lever is sticking sometimes, especially at low speeds. I did check that there is enough grease. It's funny that it won't happen if I go all the way to reverse, only if I'm, say, going downhill at low speed or negotiating obstacles. Sometimes I have to push the lever forward to get it to release. Any ideas what could be causing this?

Thanks