So, looking at your piece in Manx Notebook, John Dumbell (b. 1767 d. 1831) is the likely father because of his family connection with the IOM, and as there were no other John Dumbells around at the time. He had no burial or will in the IOM because he was based in Warrington, but presumably visited his relatives in the IOM. He doesn't seem to have left a PCC will, but possibly left a local one. (Held at local RO.)

John d.1831 the year after illegitimate John was born, so rather than being errant he might have been unwell, and we don't know whether or not he provided for the baby. - Illness and absence would also be reasons for his not being brought before the court.

Sue