Sprung rhythm is a complex poetic metre invented and used by Gerard Manley Hopkins. We re-examine and amplify a seminal analysis of this metre by Kiparsky (1989). We coded the sprung rhythm corpus for stress, weight and phrasing, then used a computer program to locate every scansion compatible with Kiparsky's analysis. The analysis appears to be nearly exceptionless. However, it is incomplete in that it permits dozens or even hundreds of scansions for certain lines. We propose a Parsability Principle for metrics mandating that ambiguity of scansion be minimised, and suggest that under this proposal, the Kiparskyan system is not a possible metre. Our own revised analysis adds ten new constraints and is cast in the form of a stochastic maxent grammar. It produces an acceptably low level of ambiguity in metrical parsing, and is supported by a good match to the diacritics Hopkins employed to mark his intended scansion.