I guess parts floating around inside the case is a pretty good indication of something wrong...
Just keep in mind the batteries determine how much current is being pulled. On my three GP24 Interstate 12VDc batteries in parallel if I run my bank down to around 12.0VDC over nite and then start charging with my PD9260C converter/charger I immediately see 14.4VDC with around 52-53 amps being demanded by the battery bank. This level starts dropping back within 15-20 minutes and levels out to around 8AMPs DC current until a two hour period goes by. Then the PD 9260c switches to 13.6VDC with around 6AMPS being demanded by the the battery for an additional hour of charge. It may then drop to 13.2VDC but as soon anything is demanded by the batteries it jumps back to 13.6VDC. Most of the time I see 13.6VDC on my meter panel unless the PD9260C goes into boost mode.
When I get my 4ea Trojan T1275 batteries in place i will want to purchase the PD9280 unit I guess. I have had great luck with the PD9260C now for over 5 years of use...
I have no idea why a couple of your caps have broken loose inside your case. My POPUP trailer is an OFF ROAD Model and things get bumped around pretty good but I would never think bumpy roads would cause some caps to pop loose.
When you look at them I would be interested to find out if the capacitor leads were ever soldered in place.
My PD9260C probably looks exactly like your PD9280. I have my PD9260C mounted to a wall just inside the trailer in a cabinet where the hot water heater is located within 5-6 feet from the battery banks mounted on the trailer tongue.
My PD9260C has performed very well over the past 5 years of bumpy use camping off the power grid.

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Roy Ken