MIAMI — Josh Richardson was unable to shoulder the burden last season. Now for the veteran Miami Heat guard, it’s about regaining his footing. After missing the second half of last season following shoulder surgery, the hope was of picking up where he left off nine months ago amid a winter revival during his second Heat tour. But now the pesky heel issue that had Richardson out at the start of the season again had him watching his steps in recent days, including missed practice time this past week. “It’s very frustrating, as a guy who tries to approach it the right way,” Richardson said, with the Heat’s attention turning to Friday night’s game against the Toronto Raptors at Kaseya Center.