526: Corrosion on PCB 
(int. print on power line for supply
transformers for field SCR's).

3437: Varistor int. from corrosion   
(RS: 240-157  PRO Metal Oxide Varistor Clamping 1200V, Varistor 710V)
FAN 110VAC => FAN 24VDC + PS (RS: 739-6547)
LC-capacitor 100nF+100R (RS: 206-7881)

Price from ebay