Reset sliders to default (zero) when a PopupMenu item is selected


I am setting up a UI with sliders that are enabled or disabled according to the item in a PopupMenu. I have been trying to figure out how to reset the sliders to the default value of zero when I select another item from the PopupMenu. After reading the documentation I think that Refresh should do the trick but I am missing something. It seems that after refresh the sliders need to be updated but I cannot figure out how. Can you help? Please see the mwe below. I am using v 12.1.1.0. Thank you!

BU

(* Initialization section *) dMin = -500; dMax = 500; dStep = 0.1; aMin = 0; aMax = 500; aStep = 0.1;  PopupMenu[Dynamic[tType], {   {0, 0, 1, 0, 0, 0} -> "t1",   {1, 0, 1, 1, 0, 0} -> "t2",   {1, 0, 1, 1, 1, 1} -> "t3",   {1, 1, 1, 1, 1, 1} -> "t4",   {2, 1, 1, 1, 0, 0} -> "t5",   {3, 1, 1, 1, 0, 0} -> "t6",   {0, 1, 1, 1, 0, 0} -> "t7",   {0, 1, 1, 1, 1, 1} -> "t8"}]  Manipulate[Grid[{    {"a", Slider[      Dynamic[aa], {If[tType[[1]] == 3 , 1.5 bb, dMin],        If[tType[[1]] == 2, 1.5 bb, If[1.5 bb <= dMax, dMax, 1.5*dMax]],        dStep}, Enabled -> tType[[1]] > 0,       Appearance -> {Small, "UpArrow", "Labeled"},       Background -> LightBlue, ImageMargins -> 0]},    {"b", Slider[Dynamic[bb], {dMin, dMax, dStep},       Enabled -> tType[[2]] > 0,       Exclusions -> {If[tType[[2]] > 0, 0, None]},       Appearance -> {Small, "UpArrow", "Labeled"},       Background -> LightBlue, ImageMargins -> 0]},(*     excludes zero from types 4 t0 8 *)    {"c", Slider[Dynamic[cc], {dMin, dMax, dStep},       Enabled -> tType[[3]] > 0,       Appearance -> {Small, "UpArrow", "Labeled"},       Background -> LightBlue, ImageMargins -> 0]},    {"d", Slider[Dynamic[dd], {aMin, aMax, aStep},       Enabled -> tType[[4]] > 0,       Appearance -> {Small, "UpArrow", "Labeled"},       Background -> LightBlue, ImageMargins -> 0]},    {"e", Slider[Dynamic[ee], {dMin, dMax, dStep},       Enabled -> tType[[5]] > 0,       Appearance -> {Small, "UpArrow", "Labeled"},       Background -> LightMagenta, ImageMargins -> 0]},    {"f", Slider[Dynamic[ff], {aMin, aMax, aStep},       Enabled -> tType[[6]] > 0,       Appearance -> {Small, "UpArrow", "Labeled"},       Background -> LightMagenta, ImageMargins -> 0]}},   Frame -> Outer, ItemSize -> {{1, 21}}],   Dynamic[tType,    Refresh[{aa = 0, bb = 0, cc = 0, dd = 0, ee = 0, ff = 0},     TrackedSymbols :> {tType}]], AppearanceElements -> None]