The back part of Watch 1 is loose and remains stuck to charger!

Hi

Whether or not it is worth paying for service compared with disposing of your damaged Apple Watch (it can be returned to any Apple Store for recycling) and/or buying a new model instead a matter for you to decide.

Apple advises that you should not continue using a damaged Apple Watch:

Important safety information

I suggest that you contact Apple Support (mail-in service may be available, if required), make a Genius Bar reservation or visit an Apple Authorised Service Provider to arrange for your Apple Watch to be inspected and to establish your available service options, timescales and cost:

• US: Apple Watch Service Answer Center - Apple Support
• Elsewhere: Select your country for Apple Watch service and repair information

Out-of-warranty repair service prices vary, depending on your location and model. Prices in the US, for example, are available here:

Apple Watch Service Pricing - Apple Support

Stop in at an Apple Store and ask how much it will cost to repair it. If you live far away from an Apple Store, call Apple Support and ask them for an estimate to repair the watch.

Whether or not it is worth the expense to repair is entirely your decision. I would recommend taking into the Genius Bar if you need more information before you make that decision: Genius Bar Reservation and Apple Support Options - Apple