TLDR: Redesigned a replacement extruder tension arm to be more durable as mine had issues from the time receiving it. May also work with Neptune 4Plus/4Pro/4/3 but do not have these machines to verify.

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Neptune4Max = N4M

Hello all,
Figured I'd share the story of what led to designing this. 10+years experience 3d printing and CAD. This is the first file that I've designed that I'm making publicly available in hopes to help if someone else had same issues I did. Since I received my N4M from pre-order(delivery date 10/27/23) I had issues with extrusion. On and off for about a month(due to not having the time to mess with it) of tinkering with this machine thinking the issues were all settings or filament related and at this point I had only printed in neutral colors(Black, White, Grey & transparent) using the N4M. With the time off work from Thanksgiving holiday I decided to disassemble the toolhead to see if I could figure out what was going on. I found green shredded filament clogging up the gears in the extruder, once removing all of this filament and reattaching the toolhead I noticed that the tension arm was cracked. I assume the green filament was from QA testing as again I had only used neutral colors to this point. I opened a warranty case(Dec 4th) with Elegoo and they quickly agreed to send me a new whole toolhead assembly, but this was coming from China(ETA was 10-20 Business days. I still have not received this yet as of posting, Dec31st, been stuck in US customs since Dec16th). I didn't want this machine sitting useless for a month so I started the repair by plastic welding and imbedding 26g copper stranded wires to re-enforce where the arm snapped. Verified the tension screw/spring were on the lowest adjustment not to break this again immediately. This held for a few days until it snapped again at a non re-enforced place. Repeated the process again at the new break and this lasted for about a week before breaking again at a non re-enforced location. At this point I decided to redesign this part from the ground up. 8 revisios to get fitment and durability right. Been in use running just about 24/7 for 10 days with no issues/wear. Changing filaments every few prints to put stress on the arm. Holds the filament tightly with no slipage and able to adjust the tension spring/screw without issue. Even have tested a couple prints with running the printer at max rated speed of 500/mms and has held without slippage. I have one installed in my extruder and a spare printed incase I run into issues for a quick swap.