Apparently the 301 and all older receivers cannot hold more than a small portion of the two-day guide at any given time. In order to search the guide, you have to position to the channel and time slot of interest, then wait for that specific portion of the guide to come down again. This can and has taken longer than the timeout period, so you may have to hit channel up/down, and/or shuffle left/right in the guide, in order to ever get this portion filled in. The guide can also get stubbornly stuck on "Info not available" for the portion of interest. In this case, the only thing you can do is cancel the guide and try again.
This is a major pain. It seems to me that the guide software needs revamping, and that $49 worth of flash RAM (or less) in each receiver (along with decent software design) could have prevented this problem entirely. It has given a bad reputation to DISH receivers that endures to this day.