its not normal for the replaced ones to explode.
it took many years for the original caps to fail, the same can be expected of the replacements.
the slow pic is likely due to cap failure, however its possible for the lamp to fail as well.
the sound circuit will need to be traced out to solve it, as it appears to no longer be an issue covered.
fortunately the sound circuit is very strait forward, any electronics tech should have no issue trouble shooting it.
the speaker is driven off the headphone jack directly.