Uneven top layer (no replies)

Good evening,

Thank you for reading my post.

Couple of days ago I have completed the built of my first RepRap Prusa 2 printer. I like it, a few things need fixing or adding, for example:
- Tighter belt tension X axis;
- Endstop flags (will print them :P)

But in my first prints I have a few issues, for which I cannot find a solution through searching. The problems are:
- Uneven fill on top layer;
- Some corners (walls and holes) have a few blobs.

If you see the attached pictures, you can judge for yourself.

Part 1; Calibration cube 20mm
Printed on standard setting slic3r; Temp heater 235, Bed Temp 100. 0.4 layer height

Part 2; Custom part
Printed on slightly lower speed; Temp heater 245, Bed Temp 100. 0.25 layer height

All printed with an acetone juice covered bed, works perfect for first layer. Nozzle diameter is 0.5, standard prusa 2 design. All axis are calibrated. Using the marlin firmware, with repetier host as control. Slic3r for the slicing.

Ive added the stl for the custom part.

Could you point me in the direction in which I can find a possible solution and or which settings to tweak?

Thank you for your time.

Here are the settings for part 2:
; generated by Slic3r 0.9.9 on 2013-05-29 at 21:05:21

; layer_height = 0.25
; perimeters = 3
; top_solid_layers = 3
; bottom_solid_layers = 3
; fill_density = 0.4
; perimeter_speed = 20
; infill_speed = 50
; travel_speed = 130
; nozzle_diameter = 0.5
; filament_diameter = 3
; extrusion_multiplier = 1
; perimeters extrusion width = 0.84mm
; infill extrusion width = 0.84mm
; solid infill extrusion width = 0.84mm
; top infill extrusion width = 0.84mm
; first layer extrusion width = 0.70mm