My motor working intermittently. Took apart per instruction (very detailed, thank you). Everything loos good on the internals. I think my problem is succumb build up on the negative spring where it makes contact on negative end of battery. I scrapped it a little with tip of knife, working some what better. Need to find small wire brush to get in there and give it a good cleaning. Thank you for your guide :)
Roger, yes, rebuilding your own pack is probably the way to go. That way you can choose thew quality/price of your batteries. I did see 4 pack 18650 already soldered together on eBay for $17, free shipping, just need to remove over-charge protector from old battery pack and install to new one. Thank you for the ideas!
Also, to replace just the battery, you don’t need to take off the side port or front cover plate. And you don’t need to remove the whole rubber case cover. Just follow the instructions for the back side panel removal only. Peel the rubber case cover from around the edges of rear face plate so plate can be removed. Becarful with rubber case cover while pulling on it as if rubber is old, it may tear at the corners.
Reverse these steps for reassembly.
Note: my rubber case cover wasn’t glued on from the factory nor did I apply glue on reassembly, I don’t plan on dropping it in the water.