The little piano awaits me

This is a little piano my father gave me about 30 years ago. My 3 children all learned to play on it and as a young adult I had lessons for about 3 years but then gave it away. However, I have returned to it over the last year and am really enjoying picking outsimple tunes and playing them ad nauseum until I feel confident with them- although I can't play without the music sheets. We have another piano in the house that plays concert pitch. This one is a semi tone out - I can't detect it but my musician / perfectionist son can't tolerate it.