Casement operator replacement

Wright, 07701-00 on the underside, original to house built in 1988. Just need to get a replacement for it.  The arm wobbles in the operator housing, so the arm drops off of the sash when the arm roller comes to the "roller escape section" of the sash's steel roller track.  I don't know who made the windows; they're poorly designed and pretty cheap. Not a surprise; the folks who lived here before me (and had the house built for them) seemingly used only the cheapest materials. Oh, well...