Bubble Lamp Hi All Is There A Way To Fix An Old Lava Lamp That Won't Bubble Up Anymore? From That Late 70,s Early 80.s.

Hi All Is there a way to fix an old lava lamp that won't bubble up anymore? From that late 70,s early 80.s. - bubble lamp

These are my parents, and she wants to work again .. The lava that separates buble, but not as it should. Thank you in advance for any answer you can give me. I'm a monster when it comes to lighting. New not so nice.