@User i have also replaced your 'a5' stimuli with a pulse gen:

clock
* a5 1 8 var_clock
* .model var_clock d_osc(cntl_array = [-2 -1 1 2]
* +                      freq_array = [1e3 1e3 10e3 10e3]
* +                      duty_cycle = 0.4
* +                      init_phase = 180.0
* +                      rise_delay = 10e-9
* +                      fall_delay = 8e-9)

** stefan added a pulse generator don't know much about above syntax and it does not appear to connect to "in" node
vpulse in 0 pulse 0 1.8 0 1n 1n 9n 20n