http://timidity-docs.sourceforge.jp/cgi-bin/kagemai-en/guest.cgi?project=timidity-bugs-en&action=view_report&id=55

--- timidity/playmidi.c	Sat Aug 28 01:38:18 2004
+++ timidity/playmidi.c	Sat Sep 10 17:07:45 2005
@@ -4160,5 +4162,5 @@
 		case 0x20:	/* Delay Send Level to Reverb */
 			ctl->cmsg(CMSG_INFO,VERB_NOISY,"Delay Send Level to Reverb (%d)",val);
-			if (delay_status_gs.send_reverb = val) {
+			if (delay_status_gs.send_reverb != val) {
 				delay_status_gs.send_reverb = val;
 				recompute_delay_status_gs();