diff --git a/src/mame/drivers/namcos2.c b/src/mame/drivers/namcos2.c
index 3cd55a0fa1d..c3802dc85c8 100644
--- a/src/mame/drivers/namcos2.c
+++ b/src/mame/drivers/namcos2.c
@@ -42,7 +42,7 @@ known issues:
     - gives ADSMISS error on startup
 
     Bubble Trouble (Golly Ghost II)
-    - not dumped
+    - MCU not dumped
 
 The Namco System II board is a 5 ( only 4 are emulated ) CPU system. The
 complete system consists of two boards: CPU + GRAPHICS. It contains a large
@@ -942,14 +942,15 @@ static INPUT_PORTS_START( bubbletr )
 
 	NAMCOS2_MCU_PORT_C_DEFAULT
 
+	// crosshair is required for gun calibration (hold 9, press F2)
 	PORT_START("AN0")
-	PORT_BIT( 0xff, 0x80, IPT_LIGHTGUN_X ) PORT_SENSITIVITY(50) PORT_KEYDELTA(8)
+	PORT_BIT( 0xff, 0x80, IPT_LIGHTGUN_X ) PORT_CROSSHAIR(X, -1.0, 0.0, 0) PORT_SENSITIVITY(50) PORT_KEYDELTA(8)
 	PORT_START("AN1")
-	PORT_BIT( 0xff, 0x80, IPT_LIGHTGUN_Y ) PORT_SENSITIVITY(50) PORT_KEYDELTA(8)
+	PORT_BIT( 0xff, 0x80, IPT_LIGHTGUN_Y ) PORT_CROSSHAIR(Y, -1.0, 0.0, 0) PORT_SENSITIVITY(50) PORT_KEYDELTA(8)
 	PORT_START("AN2")
-	PORT_BIT( 0xff, 0x80, IPT_LIGHTGUN_X ) PORT_SENSITIVITY(50) PORT_KEYDELTA(8) PORT_PLAYER(2)
+	PORT_BIT( 0xff, 0x80, IPT_LIGHTGUN_X ) PORT_CROSSHAIR(X, -1.0, 0.0, 0) PORT_SENSITIVITY(50) PORT_KEYDELTA(8) PORT_PLAYER(2)
 	PORT_START("AN3")
-	PORT_BIT( 0xff, 0x80, IPT_LIGHTGUN_Y ) PORT_SENSITIVITY(50) PORT_KEYDELTA(8) PORT_PLAYER(2)
+	PORT_BIT( 0xff, 0x80, IPT_LIGHTGUN_Y ) PORT_CROSSHAIR(Y, -1.0, 0.0, 0) PORT_SENSITIVITY(50) PORT_KEYDELTA(8) PORT_PLAYER(2)
 	PORT_START("AN4")
 	PORT_BIT( 0xff, IP_ACTIVE_LOW, IPT_UNUSED )
 	PORT_START("AN5")
@@ -4896,7 +4897,7 @@ GAME( 1991, sgunner2, 0,        sgunner,  sgunner,  sgunner2, ROT0,   "Namco", "
 GAME( 1991, sgunnr2j, sgunner2, sgunner,  sgunner,  sgunner2, ROT0,   "Namco", "Steel Gunner 2 (Japan)", 0 )
 GAME( 1991, cosmogng, 0,        default,  default,  cosmogng, ROT90,  "Namco", "Cosmo Gang the Video (US)", 0 )
 GAME( 1991, cosmognj, cosmogng, default,  default,  cosmogng, ROT90,  "Namco", "Cosmo Gang the Video (Japan)", 0 )
-GAME( 1992, bubbletr, 0,        gollygho, bubbletr, bubbletr, ROT180, "Namco", "Bubble Trouble (Japan)",GAME_NOT_WORKING )
+GAME( 1992, bubbletr, 0,        gollygho, bubbletr, bubbletr, ROT180, "Namco", "Bubble Trouble (Japan)", GAME_IMPERFECT_GRAPHICS )	/* missing external artwork */
 GAMEL(1992, finalap3, 0,        finallap, finalap3, finalap3, ROT0,   "Namco", "Final Lap 3 (World)", GAME_IMPERFECT_GRAPHICS, layout_finallap  )
 GAMEL(1992, finalp3j, finalap3, finallap, finalap3, finalap3, ROT0,   "Namco", "Final Lap 3 (Japan)", GAME_IMPERFECT_GRAPHICS, layout_finallap  )
 GAME( 1992, luckywld, 0,        luckywld, luckywld, luckywld, ROT0,   "Namco", "Lucky & Wild", 0 )