I recently purchased a used tektronix 434 oscilloscope. I noticed that the nameplate carries an "option 1". I don't suppose anyone knows what option 1 on this unit is. I also noticed that there is no persistence adjustment on the scope and it is exhibiting a little "bloom" around the edges of the two storage fields. On the plug-in style scopes when this occurred it was typically because you had the persistence out of adjustment. I haven't gotten a manual yet but does anyone know offhand if there is an internal adjustment to correct this?