Surprisingly you can pop the trackball assembly off to replace! Here is the part you'll need: [https://www.walmart.com/ip/Blackberry-Trackball-Replacement-for-Blackberry-Curve-8300-Pearl-8100-Series-White/154196604?wmlspartner=wlpa&selectedSellerId=395&adid=22222222227042696947&wl0=&wl1=g&wl2=c&wl3=107049408917&wl4=pla-297434973437&wl5=9001880&wl6=&wl7=&wl8=&wl9=pla&wl10=111838694&wl11=online&wl12=154196604&wl13=&veh=sem|Blackberry Trackball Replacement for Blackberry Curve 8300 & Pearl 8100 Series - White] and here is the guide to replace it: [guide|8833|Blackberry Curve 8330 Track Ball Replacement].
As long as the hall sensors are working you should be fine.