My 610 has both manual & automatic oiler, the manual is operated by a push button near lh side of throttle. Auto oiler can be seen by removing the top cover and is in front of the air cleaner housing, its plastic body held in place by 3or4 screws it a biege colour& about 2.5" x 1.5"... you will see 2-3 holes going vertically down, one will allow a piece of wire to clear the hole into the crankcase which is required to allow pressure pulse from engine to operate the diaphram the pushes the oil to the chain, it may be that the diaphram is damaged & needs replacing. It can be found by unscrewing the 3? screws from the underside of the pump you first removed. It would be helful to check that the oilway to the chain is clear by careful use of compressed air. Good luck