Chosen Solution
Vtech first steps baby walker not making any sound despite new batteries. There doesn’t appear to be any battery corrosion and used several different batteries
It could be that the speaker is burning out (bad speaker), or the wires are not making a strong enough connection to the speaker (one could be unsoldered). You could take it apart and try to examine the speaker and the wires that are attached to it. The speaker could have rust on it or the wires could possibly be split.
