"The most common failures of the HF150 and HF225 occur after local
electrical storms. With the HF150 the first mixer (Q22 SL6440C) fails
causing the set to have low sensitivity and overload easily. With the HF225
you get no operation over half the frequency range. Diode D1(BA244 or any
low capacitance switching diode) has probably failed, this is in one corner
inside the tin box enclosure."

The above quote is straight from this website:
http://www.lowe.co.uk/retail_secondhand.htm

Pete