Collins 75A3 Question about BFO and Other Problems

[K8JLY]

I have a Collins 75A3 that I have owned for over 40 years.  I stopped using the radio about 1983.  I used this receiver on CW, SSB  and RTTY regularly.  I decided to get the old receiver out and operating again.  Did the preliminary cleaning and inspections.  At this time I noticed it had a 6BE6 in place of the 6BA6 BFO oscillator.  When I powered it up it seemed to work except no BFO.  I put the 6BE6 back in the BFO oscillator socket and it worked.  Question 1)  Was this some kind of modification done to these receivers.  I cannot find any mention of this change.  2) The receiver seems to have a high noise level and I can't remember if it was always the case.  3) The S-Meter operates but does not reflect received signals no matter what adjustment I make.  I haven't gone through the components on the AVC / Detector string as yet.  Any information is appreciated.

Thanks,
Cid -- K8JLY

[Pete, WA2CWA]

Ham Radio Magazine ran an article on changing out the 6BA6 BFO to a 6BE6 for product detector/VFO operation.  Adds some minimal parts and some minor circuit changes. Maybe that was the plan or maybe someone mistakenly just stuck a 6BE6 in the socket.

[K9DXL]

Re:  The S-meter.  The meter adjust pot may be dirty after years of disuse. Rotate through its adjustment range, clean with DeoxIT or other contact cleaner.  Might be the easy fix.