The Model 37-116X can fail to oscillate between 530 KC and 900 KC and failure to track on the middle of the broadcast band. This can be traced to condenser No. 33 in Servcice Bulletin No. 222-A. This is a 250 mmf. condenser [or 250 pf. these days] which occasionally changes its capacity value. Correction can be made by substituting a new condenser. [I would recommend a silver-mica type for stability.]
From the Philco Serviceman – June, 1937.