It would be helpful to know what "sometimes does not work." One of the most common problems with the Autostar handsets is just that some of the buttons don't activate. That can often be fixed by pulling the handset apart and cleaning the contacts beneath the rubber button sheet. Some suggest using a cleaning kit made for keyboards, while others have just used a clean pencil eraser.
Andrew has already listed Autostar models that will work. Some might lack some convenient functions, but still control the mount. There also is an "Autostar ETX" that I was able to use with my LXD55 and 75 mounts. I believe it was packaged with some ETX Maks during some period in the past, but I found it to be functionally identical to the 497.
Also, with the addition of a Meade 505 cable, the LXD55 can be controlled with a laptop using ASCOM drivers and programs such as Stellarium and Kstars. This still requires the handset to be present and connected, because the cable connects to a second jack on its bottom, but if the handset problem is just some inoperable buttons, that doesn't usually affect laptop control.