Date registered: Aug 2011
Vehicle: 1994 E320 wagon, 1999 E320 wagon, BMW Z3
Location: Edmond, Oklahoma
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Becker volume knob fix
I have a 94 wagon that came with a Becker 1492 and it had the problem with the volume knob pot not working correctly. I pulled the unit and discovered that it was a sealed pot so I ordered a Becker 1692 on Ebay that bolted right in as a direct replacement. However, it had the same problem. Here is what I did to my 1692 and to a friend's 1692 in his 97 W210. After about a month they are both still operating perfectly. This will also work on the 1492 and possibly many others.
I used the Deoxit shown in the picture below. I bought this at Guitar center and have great success on cleaning the pots on old stereos, guitars, amps, etc. It cleans and lubes the pot and seems to be a long term fix. It is easy to find on-line.
When you remove the volume knob you will see a shoulder where the post enters the pot. I dug through my junk drawer and found a piece of plastic semi transparent tubing with an ID of 1/4" and an OD of 3/8". The OD was a bit too large to fit through the faceplate so I ground it down a bit as shown in the photo to allow clearance. As I recall I bought this tubing at ACE hardware for an unrelated project.
Once it would fit I pushed it securely onto the shoulder of the pot as shown in the photo. I then inserted the spray nozzle and sprayed a bit of fluid into the tubing until I could see fluid about 3/4'' deep in the bottom of the tube. I used a shop rag wrapped around the top of the tube so fluid wouldn't spray back into the car.
I watched it for a while and could not see any difference in the fluid level in the tube so I put my lips around the tube and blew to create a bit of pressure and sure enough, a few puffs and I could see the fluid level drop as it forced the fluid between the shaft and the shoulder. I then carefully removed the tube by holding my rag on the end and tilting it down and off as to not dump the remaining fluid behind the face plate.
Now I took a 8" section of fuel line that fit snugly on the shaft and used it to work the shaft back and forth to help the Deoxit clean the contacts in the pot. I even ended up chucking the end of the fuel line into a cordless drill and using that to work the shaft back and forth.
So far both pots that I have done this to are both working as new. I hope someone can benefit from this and I appreciate all of the work from others who take the time to post repair info on this forum.