Old battery's probably swelled up and that's why it's getting stuck. Don't be shy about removing the entire top cover and front of the frame, if needed.
These aluminum hold-downs are available polished or powdercoated in almost any transparent color. Pictured are the traditional Matte Black and Transparent/Candy Red versions. The Hot Rods by Dean ...
The Typhoon-BTW Battery Tray Washer has a reciprocating nozzle manifold with precision-aimed nozzles that surround the workpiece — traveling back and forth along the length of the battery tray — ...