diff --git a/src/all_building_blocks/base_building_blocks.jl b/src/all_building_blocks/base_building_blocks.jl
index bf59784940f63be052b28a8075687261e212ad24..cb8c762b79bde53fa0d555d767521620ed104367 100644
--- a/src/all_building_blocks/base_building_blocks.jl
+++ b/src/all_building_blocks/base_building_blocks.jl
@@ -119,20 +119,27 @@ function waveform_sequence(bb::BaseBuildingBlock, first, last)
             current_grad_key = key
             current_start = nothing
         end
-        if key == first
+        if key == first || key == Val(first)
             @assert !started
             started = true
             current_start = effective_time(bb[key])
         end
-        if key == last
+        if key == last || key == Val(last)
             @assert started
             if isnothing(current_start)
                 push!(parts, (current_grad_key, split_gradient(bb[current_grad_key], effective_time(bb[key]))[1]))
             else
                 push!(parts, (current_grad_key, split_gradient(bb[current_grad_key], current_start, effective_time(bb[key]))[2]))
             end
+            return parts
         end
     end
+    if !started
+        error("Starting index of $first not recognised.")
+    end
+    if !isnothing(last)
+        error("Final index of $last not recognised.")
+    end
     return parts
 end
 
diff --git a/src/all_building_blocks/spoilt_slice_selects.jl b/src/all_building_blocks/spoilt_slice_selects.jl
index 5c88491b4ea1b6d8183e1d10035832d530114e02..7345b8d172c1a71e6e234928b1b3b88affdbde63 100644
--- a/src/all_building_blocks/spoilt_slice_selects.jl
+++ b/src/all_building_blocks/spoilt_slice_selects.jl
@@ -38,7 +38,7 @@ end
 function SpoiltSliceSelect(pulse::RFPulseComponent; orientation=[0, 0, 1], group=nothing, spoiler_scale=nothing, slice_thickness=nothing, kwargs...)
     model = global_model()
     res = nothing
-    if isinf(slice_thickness)
+    if slice_thickness isa Number && isinf(slice_thickness)
         rise_time_var = get_free_variable(nothing)
         flat_time_var = get_free_variable(nothing)
         res = SpoiltSliceSelect(
@@ -70,9 +70,9 @@ function SpoiltSliceSelect(pulse::RFPulseComponent; orientation=[0, 0, 1], group
         for time_var in (res.rise_time1, res.flat_time1, res.diff_time, res.flat_time2, res.fall_time2)
             @constraint model time_var >= 0
         end
-        @constraint model res.diff_time <= res.rise_time1
-        @constraint model res.diff_time <= res.fall_time2
-        @constraint model qval(res, nothing, 1) == qval(res, 1, nothing)
+        #@constraint model res.diff_time <= res.rise_time1
+        #@constraint model res.diff_time <= res.fall_time2
+        #@constraint model qval(res, nothing, 1) == qval(res, 1, nothing)
     end
 
     if !isnothing(spoiler_scale)