ServoTimeTimer1.cpp does not compile

#include <ServoTimeTimer1.h>

#define servoPin1 9
#define servoPin2 10
#define potPin1 0
#define potPin2 1

ServoTimeTimer1 servo1;
ServoTimeTimer1 servo2;

int val = 0;
int dir = 0;
int pot;
int ster = 0;

void setup()
{
  servo1.attach(servoPin1);
  servo2.attach(servoPin2);
  Serial.begin(38400);
}

void setServos(int ldir , int rdir)
{
  Serial.print(1500+rdir*50);
  Serial.print(" | ");
  Serial.println(1500-rdir*50);
  // Linkes Servo (left servo)
  servo1.write(1500-ldir*50+35);
  // Rechtes Servo (right servo)
  servo2.write(1500+rdir*55+40); 
  }

void loop()
{
  val = 0;
  dir = 0;
  for (int i=0; i<11; i++){
    val = val + analogRead(potPin1);
    dir = dir + analogRead(potPin2);
    }
  pot = (val-5120)/512;
  Serial.print(pot);
  Serial.print(" | ");
  ster = (dir-5120)/512 ;
  Serial.print(ster);
  Serial.print(" | ");

setServos(pot+ster, pot-ster);
    
//delay(5);  // just enabling this line makes the servos not working anymore (random(?) initial velocity)
        
}

This is the actual (working) code of my little light following "robot" (a half-dead cockroach is much more intelligent ;-)).

Uncommenting the last line with "delay()" will make it fail.

Carsten