On 1985's Working It Back, Teddy Pendergrass regained the full vocal power he'd lost after his debilitating 1982 auto accident. The good news about Truly Blessed is that he has now also regained the elasticity of phrasing that always made his burly baritone so surprisingly graceful. The bad news is that the songs on Truly Blessed are generally mediocre ones unworthy of Pendergrass' artful efforts. He's fallen into the trap that's also snared other veteran R&B acts recently, including Smokey Robinson and the O'Jays Pendergrass is trying to compete with new-jack-swing whippersnappers such as Guy and Bobby Brown. Thus Truly Blessed is divided into a ''Slam Side'' and a ''Slow Jam Side,'' the first containing fashionably funky beats and occasional rapped interludes that make Pendergrass seem like little more than what he is a middle-aged pro trying in vain to ride the latest trend. The ''Slow Jam'' songs are too sweet but work better, because they showcase Pendergrass' strength as a soulful balladeer. Ultimately, however, the best song on Truly Blessed is its oldest one-an urgent yet subtly crooned version of the Bee Gees' ''How Can You Mend a Broken Heart.'' On that one, Pendergrass proves he can still break, mend, and melt hearts with the best of them.