Arri SR2 - Troubleshooting Lost Loop Issues

Jordan Pellegrini · October 13, 2025

Hey all, new to this forum. I was on a shoot recently and we had some issues with an Arri SR2 camera. Hoping for some insight on what may have happened.

At the start of the day I loaded the mags, set the loop and clicked them into the camera. The camera ran smoothly for about 90’ then started to make a loud clicking and grinding sound. Because of the sound I reloaded to another mag. The second mag ran for about 100’ and then the same issue. This mag actually jammed and when pulled from the camera the film had accordion-ed on the take up and feed side in the throat. (It’s worth noting, when the first mag sounded off we were at 30fps for the shot. We went back to 24fps for the rest of the day after that.)

When I downloaded the mags, there seemed to be nothing wrong on the feed or take up side. The film was wound tight and aside from some busted perfs at the tail from the second mag that jammed everything felt normal.

This problem persisted throughout the day at different intervals after I re-strung the mags. The camera would make loud, clicking sounds as if it was jamming but would continue to run. I repeatedly re-engaged the mags but the problem would persist. We did have a third mag that never jammed or produced noise which was odd. It was loaded with a 500T 250’ short end whereas the rest were 250D factory loads. Shot about 150’ on the 500T.

We got the footage back and there were definite registration issues. A couple shots were completely blurred. A few portions of film appeared streaky and flew by like a train passing. Looking at the negative we could see indents between the perfs where the registration pin or claw may have been hitting for those sections.

After the shoot I tested the camera to try to find the issue. I unfortunately only had an 80’ short end to test with. The mags ran smooth but I did notice a slight increase in clicking sound when they got up to ~60’. The SR2 we were using had a Gold Mount battery adapter that plugged into the 4-Pin XLR port at the back of the camera and magnetically clicked to the back of the mag. I tested the voltage on this plate and it remained regulated 12V even when I ran one of our batteries (Anton Bauer XT90) down to 5%. The batteries voltage also remained around 13V when low.

Any insight into what this problem may have been is appreciated.

Simon Wyss · October 13, 2025

Jordan, would you mind sending me a photo of the uncleaned, untouched camera gate, if possible? I can upload it to the forum. If not working via PM, send to my E-Mail address

Dom Jaeger · October 13, 2025

Camera and mags been serviced recently? First time using it or regularly used?Experienced loading SR mags?

It’s curious that 2 mags had the issue with the same stock, but the third with different film was ok. Also curious that it happens only after about 100 ft, suggesting it’s a take-up issue.

Do the mags feel ok - not stiff to turn, take up spindle slips with moderate force if you hold the drive gear? Drive gears missing any teeth?

This isn’t the sort of fault caused by power/battery problems.

It might be worth taking the kit to AM Camera for a checkup.

Jordan Pellegrini · October 13, 2025

The camera’s been regularly used. It’s owned by the DP so I’ll ask about its service record and suggest he take it in to AM for a checkup. I’ve loaded SR3 mags but this was my first time working with an SR2.

The mags felt fine when prepping and when I checked after the job. Take up spindle did slip with moderate force when I held the drive gear. When offloading the footage everything inside the mag felt normal.

Jordan Pellegrini · October 13, 2025

3 hours ago, Simon Wyss said:

Jordan, would you mind sending me a photo of the uncleaned, untouched camera gate, if possible? I can upload it to the forum. If not working via PM, send to my E-Mail address

Hey Simon,

I don’t have access to the camera right now but once I can get ahold of it I’ll send a photo of the gate.

Simon Wyss · October 13, 2025

Terrific, looking forward to it.

Tyler Purcell · October 13, 2025

Looking forward to seeing the photos of the gate too. I sent you a DM Jordan.

Aristeidis Tyropolis · October 13, 2025

Let's also follow up here as well on what the issue was after all - should be an interesting investigation

Simon Wyss · October 14, 2025

Pictures from Jordan, only cropped for upload

Aristeidis Tyropolis · October 14, 2025

Interesting, Is the pull-down claw side railing seriously scratched, or is it some sort of residue?

Dom Jaeger · October 14, 2025

I’d say that mag drive gear is your problem.

Each time a drive gear tooth slips the loop shifts internally. Eventually a bad loop causes film to chatter then jam.

AM Camera might have spares. Might be worth having them check the movement after punching holes and being stressed over the duration of multiple mags.