It’s a far amount of work to get to the hinge which is inside the housing. Even still that’s what I would do.
As far as your SSD that should be fine. Depending on what the new system has for RAM I would boost it to 16GB while in there.
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Basically, just follow this guide as the foot hinge is just behind it.
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Basically, just follow this guide as the foot hinge is just behind it [https://www.ifixit.com/Guide/iMac+Intel+21.5-Inch+EMC+2389+Logic+Board+Replacement/6288]
It’s a far amount of work to get to the hinge which is inside the housing. Even still that’s what I would do.
As far as your SSD that should be fine. Depending on what the new system has for RAM I would boost it to 16GB while in there.