diff --git a/frappy_psi/phytron.py b/frappy_psi/phytron.py
index ca437255..d4680afc 100644
--- a/frappy_psi/phytron.py
+++ b/frappy_psi/phytron.py
@@ -43,8 +43,7 @@ class PhytronIO(StringIO):
                 _, _, reply = super().communicate('\x02' + command).partition('\x02')
                 if reply[0] == '\x06':  # ACK
                     break
-                raise CommunicationFailedError('missing ACK %r (cmd: %r)'
-                                               % (reply, command))
+                raise CommunicationFailedError(f'missing ACK {reply!r} (cmd: {command!r})')
             except Exception as e:
                 if itry < ntry - 1:
                     warn = e
@@ -70,13 +69,13 @@ class Motor(HasOffset, PersistentMixin, HasIO, Drivable):
     encoder_tolerance = Parameter('', FloatRange(unit='deg'), readonly=False, default=0.01)
     sign = PersistentParam('', IntRange(-1,1), readonly=False, default=1)
     encoder = Parameter('encoder reading', FloatRange(unit='deg'))
-    backlash = Parameter("""backlash compensation\n
-                         offset for always approaching from the same side""",
-                         FloatRange(unit='deg'), readonly=False, default=0)
+    backlash = PersistentParam("""backlash compensation\n
+                               offset for always approaching from the same side""",
+                               FloatRange(unit='deg'), readonly=False, default=0)
     target_min = Limit()
     target_max = Limit()
     alive_time = PersistentParam('alive time for detecting restarts',
-                                 FloatRange(), default=0)  # export=False
+                                 FloatRange(), default=0, export=False)
 
     ioClass = PhytronIO
     fast_poll = 0.1
@@ -86,19 +85,19 @@ class Motor(HasOffset, PersistentMixin, HasIO, Drivable):
     _reset_needed = False
 
     def get(self, cmd):
-        return self.communicate('%x%s%s' % (self.address, self.axis, cmd))
+        return self.communicate(f'{self.address:x}{self.axis}{cmd}')
 
     def set(self, cmd, value):
         # make sure e format is not used, max 8 characters
-        strvalue = '%.6g' % value
+        strvalue = f'{value:.6g}'
         if 'e' in strvalue:
             if abs(value) <= 1:  # very small number
-                strvalue = '%.7f' % value
+                strvalue = f'{value:.7f}'
             elif abs(value) < 99999999:  # big number
-                strvalue = '%.0f' % value
+                strvalue = f'{value:.0f}'
             else:
-                raise ValueError('number (%g) must not have more than 8 digits' % value)
-        self.communicate('%x%s%s%s' % (self.address, self.axis, cmd, strvalue))
+                raise ValueError(f'number ({value}) must not have more than 8 digits')
+        self.communicate(f'{self.address:x}{self.axis}{cmd}{strvalue}')
 
     def set_get(self, cmd, value, query):
         self.set(cmd, value)
@@ -126,7 +125,7 @@ class Motor(HasOffset, PersistentMixin, HasIO, Drivable):
             enc = self.read_encoder()
         else:
             enc = pos
-        status = self.communicate('%xSE' % self.address)
+        status = self.communicate(f'{self.address:x}SE')
         status = status[0:4] if self.axis == 'X' else status[4:8]
         self.log.debug('run %s enc %s end %s', status[1], status[2], status[3])
         status = self.get('=H')
@@ -163,6 +162,7 @@ class Motor(HasOffset, PersistentMixin, HasIO, Drivable):
                 self._mismatch_count = 0
                 self.status = IDLE, ''
                 self.value = pos
+                self.read_encoder()  # let encoder quickly match value
                 self.saveParameters()
             self.setFastPoll(False)
         return pos