The "tube" will probably be an electrolytic capacitor - it's relatively rare for them to blow up but not completely unknown... Sometimes (usually) when an electronic component blows up or melts it's because something else failed and too much current flowed - melting the blown up component. Not always the case though with capacitors so you may well get away by fitting a replacement capacitor... if you can read the spec from the remains of the case. Two ratings - the capacitance usually in Micro Farads (uF) and the voltage - the maximum voltage the capacitor can withstand - go for a match on uF and anything the same or more on voltage - about 50p from an electronic hobby shop.
