Well, rather than a repair, I just moved into our house (3 years old) and the third car opener has never worked right. It initially would go up, but not down, and didn't stop at the top, it just jammed and vibrated against the opener unit. I opened it up to find that somehow the open adjustment stop was bent and the locator just went right by it and kept trying to go up. I righted that situation by bending the stop back and setting the open travel adjustment properly. So now, it will open, and when hitting the stop, does stop. But, it will not close. I can manually close it by removing the belt from the motor and getting everything set at the bottom, then push the button and it opens again and stops properly at the top. Holding down the button does no good, and I can confirm the photo sensors are aligned properly because if I block them, the opener lights come on. It just seems to me that whatever switch exists to tell the opener it is at the top and needs to reverse direction has failed, but I have no idea what that is or how to fix it. I did find the start capacitor you guys were talking about (big blue guy, 4 wires, two red, two blue). My terminals are top and bottom, with connections on each side of it. The reds are on the bottom, and the blues on top. My opener is model 139.53954. Thanks for helping.

See your other post.

Remove the cover and take a look at the drive gear which is right in front of the motor. It is white nylon and is probably stripped. You will most likely find a lot of white 'sawdust' inside the cover. If that is actually your problem you can order the gear from Sears or any local opener dealer. The part number is 41A2817 and supposedly comes with instructions.

'96 Craftsman 139 53648SRT model 1) problems closing....go down a lil a come back up. RPM sensor I suspect ??? 2) LED flashing 5 times.....RPM sensor ? 3) while researching above problems...now when the remote or wall unit (no pad) is engaged, there is nothing but a slight/quick "humming" noise..and nothing happens. This is a new symptom. 4) I have checked/tired to align the infra red sensors.... this model has both lights on constant, regardless of whether they are in sync or not. I checked the wiring from teh sensors back to the motor/unit. I'm not sure how to align them now. QUESTIONS: which do I address first ? I'm not sure I can align the infra red sensors without the "humming" and no activity when I engage the opener. Should I look at the RPM sensor first ? Is the gear stripped ??? causing the humming and non activity ? The opener was opening before I started working on it. Thanks to anyone and everyone who has advice on this.