Sony SL-2401 Betamax VCR
Sony Beta VCR from the 80s
Canadian Sony Betamax SL-2401 VCR was introduced around 1983. It continued the remarkable success of its predecessor, the SL-2300s. The SL-2401 has a smoother case design while retaining the beloved centralized button array. Notably, Sony included the infrared remote option starting with SL-2400 series.
Encountering a Betamax VCR bundled with a handful of tapes at an attractive price, I was eager to delve into the intricacies of VCR technology and explore the nuances that set Betamax apart from VHS. Buyer did warn me repair was needed on the unit. As soon as I plugged in to test, it became evident that the unit was plagued with several issues. Initially, the tape loading mechanism proved problematic, frequently getting stuck and failing to load the tape properly. Also, when playing videos, the picture showed some sort of static noise in regular cadence and the sound was distorted or garbled, so watching anything was nearly impossible. I decided to address these issues head-on and restore the functionality of this set and bring it back into service.
Sony SL-2401 specs
- Chassis: 711B
- Wireless Remote Control
- Plays Beta II and Beta III
Tape unable to open when loaded issue
It seemed that the problem lay in the metal clip that opens the tape. I found that bending it a bit more helped the tape load reliably. I tested loading the tape multiple times to understand why the guard panel wasn't opening, relying on my intuition to reach this conclusion. Unfortunately, there wasn't much information online about this particular issue.
You have to remove 4 screws to open the top panel. 
Fixing the video issue
After considering various possibilities suggested by members of the Facebook group "Beta is Better!!", I ultimately pinpointed the issue to a tracking problem. With valuable guidance from knowledgeable individuals within the group and a helpful video by 12voltvids on YouTube, I managed to resolve the problem. While it's not flawless, the improvement was substantial.
Removed the tracking potentiometer 
When I opened the potentiometer, I discovered that the metal wipers had separated from the white rotary plastic. It seemed likely that this was caused by the aging of the plastics.
Super glued metal wipers to the plastic. The bottom wiper is used to feel the middle point of the potentiomenter.
I removed the tracking potentiometer and found that the metal brushes, two in total, had become dislodged from the white plastic shaft. These were very small parts. Using super glue precisely, I carefully reattached them to their original positions, guided by two small bumps on the white plastic. Additionally, I gently cleaned the carbon track with isopropyl alcohol. After letting it sit for an hour, I reassembled everything. Testing the resistance between the center pin and one of the edge pins, I found it to be around 45 kohms, which was a good reading for when the tracking was in the middle. I then soldered the potentiometer back onto the unit, and the problem was resolved! Below are some pictures showing the process.
In case you are looking for a replacement potentiometer, these were the dimensions.
Cleaning the hall effect sensor glue
I received advice to inspect the hall effect sensor of the drum motor for dried-up circuit glue. If it appeared crusty and brown, it needed to be scraped off to prevent potential issues in the future. Taking heed of this advice, I cleaned it up while I was attending to other tasks.
There were 10 screws on the bottom panel to unscrew.
See before and after cleaning the hall effect sensor below.
Turning off PCM switch at the back
After addressing various issues, I found that everything looked perfect when playing the Betamax tapes, except for occasional white lines known as dropouts. Upon receiving advice from Fivos Sakellis in the Facebook group, I turned off the PCM switch, and the issue vanished. With this final adjustment, I now had a fully functional Betamax machine to enjoy!
More Pictures
Static when tape is stopped 
Betamax front 
Betamax side view 
Capstan motor 
Power supply 
Top board 
Bottom board 