Originally Posted by
alecd
Could be a poor-quality no-name tool. I've also noticed that Falcon and Tiger freewheels (often found on low-end bikes) use a very similar, but slightly different splined remover tool. Perhaps your no-name tool is intended for Falcon or Tiger freewheels.
In any case, a new tool is needed. Get the official Shimano TL-FW30 or a reputable (e.g. VAR RL-41100 or Park FR-1.3) copy.